You can copy over the .tga files as you did, but you need to do it for both ui/unit_info & ui/units. However BMDB will require that you know what you are doing. I HIGHLY recommend that you make a copy of BMDB before messing with it. I also will not give a full tutorial on how to change BMDB correctly, you will need to do research on your own. I will just give general info. If you mess up you game, you are on your own.
In export_descr_unit:
- Find the unit you want to change (Zhao Yun's buqu is named JiangJun_ZhaoYun)
- Near the end of the unit's entries, you will see the Ownership, Era 0, and Era 1 entries
- Add whatever factions you want to this for all three of those entries
- Find the "soldier" entry for this unit (soldier should be named yanyuntieqi)
- As a note, you can add russia and aragon to this, as they already have the BMDB entries (for a different unit that uses the same model/texture). Although you would still need to copy over all sets of .tga files.
In battle_models.modeldb:
- Find the soldier entry for Zhao Yun's buqu (yanyuntieqi)
- You will see that each faction has 2 separate entries (one is 4 lines, the other is 3 lines). Those two entries are required for each of whatever factions you want to add.
- Copy the entirety of the "aragon" entries and past them below their corresponding existing aragon entries.
- change the words "6 aragon" in the new entries you just made to whatever faction you want. The number is how many letters are in the line after it (ie: 7 normans , 5 egypt, etc.)
- Now, depending on how many factions you added, you need to change two more numbers. Locate the "4" located directly above both "russia" entries. Change those 4 entries by adding however many factions you just added. If you added 1 faction then change both 4's to 5, if you added 2 factions then change those 4's to 6, etc.
Now Zhao Yun's personal unit should be available to the other factions you added if he joins them. Be aware that this WILL NOT allow Zhao Yun's personal battle model to be used, as battle models are tied to traits and other files that require a lot of editing and messing with game files.
Adding only the england (Cao Clan) faction to BMDB will look like this: