How about reborn souls and their family tree?

I want to test it with my Snow White's Descendants legacy household but I'm too skittish to try that right now.  I'm only a vanilla player in my PC games & I don't have a supercomputer with billions of storage, so I'll wait until it's safe to try it.

I don't have the pack yet, but I'm interested to hear how this works.

My reborn Sim moved in with the Landgraabs as an infant, but they don't show up in her family tree. She started as an elder in my game, so she didn't have parents from her previous life. I guess that answers half your question.

Ah, that's interesting. Would actually be fun "pretending" being someone's real child while soul actually belongs in a different family :)

Ah no... I forgot to test it.

Hmm... This is a good question. You can set the new family relationships when creating the reborn sim, but if they have a new family tree and whether the old family's tree will be affected, that I don't know...

Unfortunately, I can test this on Saturday.

I did some testing. My reborn sim showed up in the family tree from the new family BUT you have to set this in CAS when they are reborn.

You can be reborn as a relative of literally anybody or just as a household member. Even if your sim is reborn as an infant, they can be related or unrelated (just a household member) of their new family. If you play with genetics to make them appear like their new family, then the family relation is set automatically (but you can remove it as long as you are in the rebirth CAS). You can set them as the child of their new family just like you do with every family you create in CAS, or not if that's what you prefer that route. So the choice is totally up to the player if they want them to show up in the new family tree or not.

Their 'old' identity is still displayed as deceased in the family tree of their previous relatives.

Thanks for testing! That's actually super cool. That we can choose their familytree status. I'm already spinning up some ideas of a dead sim from family X being reborn into family Y in order to grow up as an insider there to revenge some old family conflict once getting old enough. A new life as a secret undercover agent, somehow :)

I didn't set relationships in CAS when Malcolm Landgraab was reborn into the Landgraab household. In his family tree, he doesn't have any parents. So your Sim loses their previous parents (grandparents, etc.) when being reborn and only gains parents if you set them in CAS.

Did the same test, got the same result. That is very cool.

Though I don't like that every time I have to save the household they were reborn into into My Library...

Did some testing as well. I used "Rebirth" for the father of my household, used the option to give him similar genetics from his previous life and moved him back to the same household. Family members were acquaintances at first but their relationship built quite fast. You can use the interactions "Talk about strange connection" or "Reconnect with Soulmate" or something like that, but would recommend re-building some relationship first (become friends or close friends) otherwise the outcome will be negative. At some point, you can Adopt your children, my sim even got back his Mother and Brother relationships without doing anything, which was pretty cool. Had to re-marry the wife though, for the third time lol