It's really confusing but I think only blood can be aunt or uncle. When a your mothers sister marries a guy he becomes an uncle by marriage.
^this
life is like that though i have an aunt who wasn't an aunt at all she was a long time family friend to one of my parents
when in the CAS try to make everyone related this is how i got it to work if you want to keep the Uncle (or aunt as the case may be }
in CAS two female two males the ladies are sisters A and B the guys brothers added three children A and B ,B1(bro and sis ) they see each other correctly as cousins deleted one female but the male she was married too is still an uncle because the other male is his brother
see images 2 (before and after ) CAS one in game
edit typo
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