Sim's disappearing from my family tree.

I'm participating in a legacy challenge, and I know they typically delete Sims from the family tree that you didn't play with in order to save space, which is fine. However, the Sims I had directly played with, but who were moved out, were deleted from the tree. Their urns are still there, and their names are still attached, but I wanted to see if this was a bug. They weren't main characters, but they shouldn't be deleted xD Luckily, I am obsessed with my family I made a handwritten family tree to remember them by.