I experienced a problem with the family tree changing relationships between sims. My sim had two kids from Sim A, but then he died. My sim married a new man, who used the Adopt interaction from the pie menu on the children from the previous man. This led to the children forgetting their birth mother completely in the family tree, and her becoming their stepmother in it and the relationships tab. It also lead to the children's birth parents to change into their birth father and the man who adopted them, who the game has now changed to have the Father title in the relationships tab and on the family tree.
The Sims Team
