I don't think it would be compatible at least not Andal, First Men, Ironborn and Dornish portraits anyway the rest of it might be alright. Probably no harm in giving it a go just make sure you back up your save before you load it in case anything goes wrong.
From my experience, it works with Congenital Overhaul. However, in some instances, the portraits of characters using the search function is sometimes broken as they are completely removed from the portrait and it's just a black circle. I normally just reload my save to fix it.
Also. there an issue with clothes when I try and edit a character's clothes and headgear in save game, it defaults back to what it was before, but that could be because of my characters traits, I know it's not the rank because they are an emperor title.
The mod runs smoothly for me, there's just two bugs that I noticed, the Yi-Tish clothes are the same as the first men's and the portrait of the people of the bone mountains, particularly the kingdom in the middle, have their hairs just floating about in the portrait.
First, I'm not sure why Yi-Ti characters are using First Man clothing, they should be using the base games muslim clothes as they normally do in the main mod, also not sure why Bone Mountain characters aren't loading in they should also be the same as the base mod, though that sounds like you don't have some of the portrait DLC. I'll take a look and see if I can figure out what's happening with both those issues. Second, I may work on making this compatible with Strong Seed and Congenital Overhaul, but my knowledge is fairly limited when it comes to modding, so that might be a while.
Also jongalicious' issue with portrait clothes and headgear changing after being edited in a save file is not a problem with the mod, it's just the way properties for portraits work, they're overridden by a character's traits, rank, society, etc.
I have fixed the problem with Bone Mountain characters, was just a simple case of me telling the game they had 2 more haristyles than they actually had. You can download the new version or you can download just eh gfx file thats affected and replace the old one.
'A Game of Thrones' is a user modification for Crusader Kings II not affiliated in anyway with Paradox Interactive or the rights holders to 'Game of Thrones' and 'A Song of Ice and Fire'.
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