I've recently been experimenting with breeding several hidden traits (immune to fire, pyro, etc.) into my Sim families. When I finished up with one family, I moved the two brothers out of the house and aged them to adults. Then I saved them to the Library. When I placed them into another town for a fresh start, they no longer show up as related to each other! I was upset because I spent days getting just the right traits and raising them up. It is important that they remain related, due to being part of a story I have in mind.
My question is, is there any way to ensure the family tree stays intact when I split the brothers from the household and move them to another town? I've considered having the parents die (I hate killing my simmies, though) and keep the tombstones/urns in the family or personal inventory, if it will keep the tree intact. Would this work? Or is it a lost cause? My game has no problems otherwise. I have all expansions and stuff packs except Fast Lane, and only use CC from the store. I do NOT use "m-word" of any kind.
I appreciate any and all help I receive. Thank you, everyone.