Solved
Can’t make two YAs brothers
Sorry if I’m posting this in the wrong place, I’m new around here. I have two YAs in the same household. One has always been in the household and the other just moved. I have testingcheats and cas....
Three years later and I just remembered about this post. I did work out the reason behind this issue a couple months after making the post; the new Sim I moved in was imported from a previous save where he had already had siblings. I probably should've realised this from the "Cannot edit pre-existing Sims" message.
Resolving this for my past self doesn't really have any purpose, but hey, maybe it'll help me sleep a little better at night having some closure on this, lol.
