So, the first thing you need to know is that each faction behaves differently regarding family trees.
The rules a faction will follow are set via descr_sm_factions.txt and are not save-compatible (unless proven otherwise, of course).

If you open the file, you'll find several sections in this form:

Some of them are quite self-explanatory: faction name, culture, religion, symbols and colours. standard_index is the reference to which position on the banners/symbolsX.tga.dds files the faction uses for its strategic map standard logo, can_sap is a RTW leftover, triumph_value is unknown.
prefers_naval_invasion seems actually working as "can make naval invasions". Since in vanilla it is usually se to "no", there is no wonder why you never see AI naval invading.

For the purpose of this tutorial, howewer, the only relevant lines are the last two: can_have_princess and has_family_tree.
The first one will be considered in the Part IV of this tutorial, now we will focus on the "has_family_tree" line.

In Medieval2, the only avaiable values were "yes" or "no". "yes" meant the classical family tree, where each general belonging to the tree is considered a "X faction family member" while others (like, some starting generals, or bribed\recruited ones) are just "X faction general". Most important, if the last family member dies, the faction is wiped out. The death_movie line then is fired, and game is over.

The "no" option is used only for slaves and papal_states, but can apply to other factions aswell. In this case, th player will not be able to open the "family tree" panel (missing UI element).
All the generals are, and this is strange indeed, "X faction family member" and there still are the Faction Leader and the Faction Heir.
There will not be new births or adoptions, so generals will have to come in some other way, but the key point is that the faction will survive even if all the generals are wiped out.

Kingdoms expansion, howewer, added a particualr feature, explicitely made for the teutonic faction in the teutonic campaign. The line for the teutonic faction is the following:
This indicates a particular type of tree, which is very similar to the "no" option, but in this case there are 2 ties of named characters: generals and family members.
Adoptions are allowed, but the faction can still survive if no generals are left.
Also IIRC there is a little bug, the faction survives even if owning no regions. This afflicted Mordor faction in TATW 1.0 (damn', I feel old now :P) and can be solved only via script monitoring the number of settlement the faction owns and eventually using the kill_faction command.

This part covers the editing of characters in family tree.

If you played M2 for enough time, you may noted no character can have more of 4 sons\daughters. This number is set in descr_campaign_db.xml, in this line:

<max_number_of_children uint="4"/>

You can lower this number but you cannot raise it. If you set a higher number, the game will not be able to read more than 4 children in descr_strat (the satring family tree).
New children may born (but will not shown in the tree) but the game will crash when they'll come of age.

There is a way to force male offspring and having more than four children (but remember that hard-coded upper limit is 4 males even with this system).

Furin wrote a tutorial about this some time ago:
http://www.twcenter.net/forums/showthread.php?t=158912

This said, let's move on the starting family tree of a faction. You set it in descr_strat.txt.

Basically there are 2 classes of chracters, dead and alive ones, and the latters are divided in adult and under-age ones.

Alive family members need to be defined in descr_strat in this form:
for generals while agents (spies, assassins, princesses, diplomats) in this way:

in the relative faction's section after the settlements' list. You can notice that the only difference is, the generals must have an army attached. Now, let's examine the entries.

The first entry "character" specifies for a character entry; it is followed by a TAB and the name (and eventual surname) of the character in question.

The second entry specifies for the charachter type (as per descr_character.txt). character_type's are hardcoded tought, generals and captains must be listed as "named character", princesses as "princess". Other legit entries are "admiral", "spy", "assassin", "diplomat", "heretic", "witch", "inquisitor". The properties of each of them are mostly hardcoded, some are set in descr_character.txt. Just know you cannot have any agent in your family tree but princesses. Witches are not suitable and kick you back to menu when starting a campaign.

Third entry is the sex, this is IMHO a redundant thing since sex is hard-coded with character_type, and is maybe a leftover code from character_records section (maybe CA wanted to allow agents to be both male and female but then ended otherwise). It may be followed by the "leader\heir" entry (only for male named characters) setting the charachter as faction leader or faction heir (or both. see later).

Also avaiable is the entry "non_family". It removes the status of a character from family tree, and cannot be appointed as Leader or Heir, nor adopted or married. It seems not working in via-script spawns but it works fine in descr_strat.

Then we have "age" and map x-y co-ordinates.

The entries "portrait" and "battle_model" are optional, they specify for custom portrait folder_name (UI\custom_portraits\folder_name) and battle model (as per battle_models.modeldb). No hardcoded limit of custom portraits or battle models is known.

Another optional entry is "off_map", wich brings off_map your character at campaign start. At least one co-ordinate must be expressed in the co-ordinates section, otherwise the general will be locked in low left corner of the map (even if it is sea). Can be unlocked with the move_character command via script tought.

Finally, there is the "label" wich is an alpha-numeic code you can assign to a character to identify him\her univocally in the campaign. Can be referenced in script and has no use out of it.

Next line is optional, is the "trait" lines and lists the character's traits as per export_descr_character_traits (trait name, level, comma)
Same applies to "ancillaries" line.

Male generals must be linked to an army, the fist unit is the general's unit while others are optional and are the generals' army.

A strange bug affects princesses custom_portraits and makes them un-usable: the portrait specified in descr_strat is shown whe clicking on the agent scroll, while when opening family tree it is shown the generic "adult woman" one.
A weird bug affects pricesses with the off_map attribute: in this case the portrait is a little vanilla one (william the conqueror). Strange indeed, this happens even in mods like TATW where UI has been completely replaced. I can't understand why this happens, but I guess that both off_map and custom_portrait attributes were made for generals, not princesses, so engine goes ballastic.

Dead and underage characters are listed in a successive section of the file, in this way:
the fist entry (character_record) indicates the start of the records' section, followed by the charachter's name and surname. Then comes the sex and age of the character at start of campaign.
Next entry can have two values, "alive" for alive characters (does not work with adult males, who need to be listed as generals) and "dead" for dead characters. "dead" can be followed by the time they are dead (how many years ago?); in the example, Harwood Karstark died 15 years ago, hence at the age of 50.

Last entry can have several values:
current_leader: underage character is the faction leader
current_heir: underage character is the faction heir
never_a_leader: default one
past_leader: the character was faction leader in his life.

Finally, at the bottom of the faction's section, comes the relatives part, each line introduced by "relative"
Here all the components of the family tree are listed, in the following order:
male character - female spouse - 1st son\daughter - 2nd son\daughter - 3rd son\daughter - 4th son\doughter.

A TAB is after "relative" and after each family member, the line is conluded by "end".

Please note that, despite the spouse being usually listed in the "character_record" section, she can also be a princesses (active on the map), but will be considered married by the engine and will not be able to perform seduction missions.

One more thing : all names and surnames used must be owned by the faction the character belongs to. Theese names are listed in descr_names.txt and are a separate entry per faction. The file itself is very intuitive and easy to modify, just remember it can only use ASCII characters and export to the text\names.txt file. In the latter each entry specifies how the name will be shown in-game.

This detail is the reason why, when a princess of yours seduces a foreign general, their children will not have the foreign surname but some random ones picked up by the engine. This is no doubt a CA fail and cannot be fixed, unless you allow all faction to have access to all surnames in descr_names.txt.

Last important thing, please note what defines if a general will belong or not in the family tree is his status as son of some other family member, OR having a wife listed in the relatives section. So if a character has no relatives but was included with his army, he will be a petty general and not a family member.
This allows you to have multiple family trees (giving each general a wife) wich can be separate each other. In this case, when opening the "family tree" panel in-game, you'll be able to see only the Faction Leader's tree. Again an hardcoded limit, no way to switch to secondary family trees is known.
I read somewhere this feature was already present in RomeTW but cannot find the source now.



For a more detailed explanation on how to extensively modify your family trees, check Advanced family trees by GrnEyedDvl:
http://www.twcenter.net/forums/showthread.php?t=187293

Also this tutorial, made by Hellenikon, may come handy understanding the difference between "general" and "family member":
http://www.twcenter.net/forums/showthread.php?t=431932

A thing that always annoyed me (and many other people) is the impossibilty to manually choose your Faction Heir. The heir is in fact appointed by the engine and cannot be changed.
The criteria the exe choose the heir when the Faction Leader dies is quite simple: the first family member with highest authority becomes new heir .
Hence you can choose your next heir, via ancillary, removing all references to authority in export_descr_character_traits.txt and export_descr_ancillaries.txt, and then creating a transferable ancillary with Authority boost effect.
The family member owning it will be picked up as Heir when the current Leader will be dead.
Such work could interfere with the whole authority-loyalty system, so some balancing and adjustments are required.

Instead, engine overrides the authority system when the Heir dies and a new one must be appointed. The criteria the exe chooses the Heir in this situation is, at present day, still unknown.

Another exception on this (thanks to Ngugi and Withwnar for reporting it) is the Teutonic tree heir, wich is the one with highest base Command attribute (instead of Authority).

Also note that there is the possibility, for a faction, to have multiple leaders\heirs. This is a buggy situation tought, expecially regarding diplomatic marriages, so it has been seldomly used in mods (actually the only one I heard using this feature was Narnia Total War wich is still WIP)

Finally, you can give the same character both the "leader" and "heir" attribute in descr_strat. This leads to a strage bug, when the character dies the current heir (himself) becomes leader, while a new heir is appointed. Hence the character will be bloody dead, but still considered "leader" in the family tree. No other Leader will be ever appointed then, since he can't die again, of course.



More info on underage leaders\heirs in this tutorial by TNZ:
http://www.twcenter.net/forums/showthread.php?t=296296

While this, by Konny, covers the heir picking matter:
http://www.twcenter.net/forums/showthread.php?t=257175

The problem of multiple heirs\leaders is considered by King William The Conqueror here:
http://www.twcenter.net/forums/showthread.php?t=515396

In descr_sm_faction there is a line:
that can be followed by either yes or no. Meaning of the sentence is misleading tought.

"yes" means the doughters of an alive leader\heir will become princesses when coming of age, while "no" means they will be considered like other generic women and will not become agents when of age.
Please note that "no" does NOT mean that the faction is not allowed to have princess, only that the leader\heir doughters will not become princesses. In fact you can always spawn them via script, or place in descr_strat, since agents avaibility is set by descr_character.txt.

The can_have_princess line has also one other, more subtle, effect.
"no" prevents the faction's generals to be seduced and disables the diplomatic marriage option for males. If, for whatever reason, the faction has a princess, she will be able to propose a marriage to another faction with "yes" value - or to seduce its generals.
This is the precise reason why muslim factions, in vanilla M2, cannot get diplomatic marriage alliances and cannot get their generals seduced.

Please note that this is NOT linked with the family tree type, so if you set "yes" to a faction with, let's say, teutonic family tree, they'll be able to accept marriage alliances and get their generals seduced. No children will born in the faction, tought.

How to spawn family members via script by OfficerJohn

Now this is actually the easy bit, as technical expertise here is unnecessary, and most of what you look for can be found online (again, consult the law first). if you do shoot it yourself, just make sure the whole person is in view, and you point it in the right direction relative to the target, and not shake around. in my case, I simply need footage of a french soldier. in this case, you want the view to be in profile--from the side. going left or right matters little, so long as the person walking is from the side. and you only really need 1 full stepping motion (a pace however is ideal). I no longer have the video I used, but it was ideal, showing reenactors in profile while marching. measurements reveal one of the men was ~6 feet tall (about that of the RTW model, scaled down), and had the correct pace length (~60-65 cm)

for this, you can download the windows movie maker, which is for free. it's not very sophisticaed, but that's alright. it has two things we need:the ability to take snapshots in a picture format, and the ability to slow down the footage (in multiples of 2. so by 2, 4, 8, 16,etc). slow it down as much as you feel comfortable (personally, I find x0.125 speed (so by 8 times) to be good), and can make out individual frames. the steps are relatively simple--if a bit time consuming, going from here:

1-first, slow down the video to an appropriate level.

2-find a point to start in (you can choose this as you see fit). take a snapshot of this. remember that you have to track only a single person, to keep the scale consistent.

3-then take snapshots at regular intervals. be precise--otherwise things will look screwy when rendered in animation in RTW. export the snapshots preferably as a png or other lossless formats, but jpg is acceptable. finally, make sure it covers the whole loop/cycle.

1-any picture editing software will do. I used GIMP.

2-create a new file, where you'll be putting the loop in.

3-take each snapshot, and cut out the relevant person/persons.

4-paste them into the new file. keep them in line, with a single reference (the ground in this case). this will save you much time and heartache. keep the proportions intact: GIMP has atool that will let you resize, while keeping proportions, should that be necessary.

do this right, and you'll get something like this:

what this means is that you must synchronize the frame rate of what you captured (in my case, 8 frames/second), to correspond to what it would be in RTW (which is 20 frames/second).

1-set the very first frame in the loop as being frame zero. the second frame is now frame 1, then 2, 3, 4, and so on, unto 10,000 frames (+rep for whoever gets the referece)

2- find the ratio between the frame rate you made, and the RTW frame rate. in my case, the ratio is 2.5:1 between the two framerates, so in this case, multiply the former's frame number by 2.5, and then add 1, to get the position in 3dsmax. doing this right, you'll get the following for 1 step:

0,1,2,3,4,5,6,7,8 ==> 1, 3.5, 6, 8.5, 11, 13.5, 16, 18.5, 21

3-don't worry about the ones with a half in them. we'll deal with it later.

1-this is straightforward: import a model of a soldier standing still (so also import the animation relevant). this is to account for different ways of carrying weapons, and will save you time. in my case, I used a french fusilier, arms shouldered.

2-create a plane (textured side facing the soldier), whose height is that of the soldier: note the height! now, this is where the proportions of the picture come in handy: you know the height of the soldier (hopefully), so with the proportions you wrote down, you can get the length.

3-import the snapshot file, and use it as the skin of the plane. if you do everything right, it should look a lot like this (well, this is after I got the animations done, but you get the idea):



4-as you can see, you need to then find a reference to calculate the displacement (i.e., step) length. that's what the boxes below the man are for.

you're now ready to make the animation!

1-start with the frames that correspond to the beginning, middle, and end, of the loop (so the beginning and end of every step). these will always be whole numbers--unless you made a mistake. first, match the pose of your model with the corresponding snapshot from the sequence. be as precise as possible. then place them in the correct position (the boxes come in handy here: you don't want either foot going into either box wilst they are still on the ground. the boxes represent toe to heel distance).

2-do the same for the whole number frames that aren't at the beginning and end of the step. note that I only have one step represented. that is fine, as one can just reverse which joints to bend, and still keep it corresponding to the picture.

3-now for the ones with half in them, you have two solutions:
a. some of you may want to change the frame rate in the time configuration button from the default 30, to 60, and work steps 1 and 2 with that, and then add the "trouble" frames in (which would now be whole numbers), after which you reset the frame rate to the default (30 fps). this would split the ones that would normally be with a half, into two separate frames (in theory at least--worked for me elsewhere).
b. the other solution--the one I went with--is to omit them unless it is necessary (to make the walk more natural), at which point I would round the frames up or down to the nearest integer (alternate them), and hope for the best. As it happened, I didn't need them, so I'm not too worried.;)

4-export the animation, and get it into the game.