Finally found an answer, gave up a million times. I started experimenting about a week ago now.Activate the cheat
: testingcheatsenabled trueShift and Click
: All sims - one after the otherThen
: Add all sims to your saved sims. -think its called something like sim bin or something?
(Create a sim) Find all your family members in default sims (or whatever it is) and Edit family tree once you have created your family, yet again.
This was the pain of my life for weeks! Accidently married my mother haha.
Hope this helps! Haven't read all of the discussion but i hope (if not already) this solves your problem!