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Sibling Marriage Only

If a character has pure blood, the character can only marry his/her siblings (Cannot marry parents,kids)
Pure blooded trait is modified so it can be inherited 100%

Modified from mod "Strictly enforced divine marriage" , original mod use faith as a trigger for family marriage.
https://steamcommunity.com/sharedfiles/filedetails/?id=2961866746&searchtext=strictly


Pure-blooded is used as a trigger because AI's religion (your family member) can be changed in the game, with this mod you can keep your holy blood forever in the house.

Check another mod of mine : Family marriage only" if you want marriage happens within your family(All close family member, not just siblings)
https://steamcommunity.com/sharedfiles/filedetails/?id=3345326287

Also try “House Marriage Holy” https://steamcommunity.com/sharedfiles/filedetails/?id=3390921274
if you want marriage happens within your entire house.

Suggested using together with "Spouse Designer" https://steamcommunity.com/sharedfiles/filedetails/?id=2829316015
You may design a spouse you like in the beginning of the game and keep your holy blood forever in the house.