Family tree making some of my sims siblings although I didnt set them to be

so, im so not sure if this is just happening to me and I have had to delete sims I spent so much time on/played a lot with.

I transferred some sims to a new save regarding the update, and so upon that i had to edit their relationships back to how they originally were (mothers, fathers, etc), however, the game os the family tree has made some sims relatives who i did not set to be as and are not related at all, for example, my sims ex husband is now her brother?? I did not do that, and it also made my sims partners their siblings too which began to mess up my family tree, so i had to delete them sims because of this, i thought it was all fixed until i start up my game again today and it made my sims ex husband her brother.

Anyone else experiencing this? or have i done something