Holy cow, I just cracked the code 😛
Here's what I did:
- Separated and created new households for all "pre-existing sims"
- example: sister and brother were in a different household as their mother, so I created a new household for the sister, new one for the brother, and a new one for their "mother"
- Saved them all individually to my library
- Created a new household in CAS
- Added all family members into "new" household individually from my library
- Modified all relationships
- WAS ABLE TO GIVE MY SIMS THEIR MOTHER BACK :D
(1 year later...)
sidenote: I have been scouring the web to make this work for WEEKS and tried EVERYTHING from -what seemed like- every forum. mods haven't been too kind to previous save files so the family I was playing with (my generation run). So, I removed them and started fresh. 6 months later, wanted to try mods again but didn't want to ruin my save files. Saved a family member, modded her, and played her quite a bit. However, I was really missing having the fam around. So I saved them and brought them to my modded save file and couldn't fix their relationships (why didn't they follow???) and came across this puzzling issue. Took matters into my own hands. Hope this helped!! (hopefully i'm not the first to figure it out either) (sry new here)