Playing Venice I noticed that there is no "Show Family Tree" button visible (you will find this for HRE as well) when the Grand Add-On is applied to the Retrofit mod.
The fix however is very easy: go into your mods/Retrofit/data folder and find descr_sm_factions.txt and change both entries for "has_family_tree" from "Teutonic" to "Yes" under the Venice and HRE sections.
That or just use this and paste over the original entries:
I admit I am curious how "Teutonic" got in there?!?!?
Best to all,
P.S. Nice mod and nice Add-On- kudo's to both of you.
P.P.S. The parsing is not correct for "yes" as shown on here on the TWC screen. It may cut n paste properly; but just double check that it matches up with the rest of the sm_factions.txt formatting.