There's a couple of things I've noticed with this game that I don't understand:
1. When I add finished house designs to my Library, the following day some are there but not others even though they were just added the night before. I save a lot.
2. Sometimes when I try to create a twin sister for one of my Sims, as soon as I choose "Create their Sibling", the person whose twin I'm creating suddenly has an exclamation mark over their icon. When the twin is finally all good to go, checking the Relationship status it says she is just everyone's Roommate, not the sister????