Okay, I just ran into a problem that I hope won't disqualify me from the challenge.
I bought a house that came with a car parked on the lot. I never touched that car, but for some reason when it was time to move, my sims used that one, and left one of their own vehicles behind, and apparently that's now part of the lot they moved out of because I couldn't interact with it when I went back for it. I had previously claimed the vehicle that was left behind as a "bought" item, so technically that's not a problem, but the car that was taken by mistake theoretically is since I didn't actually buy it - would it be adequate for me to claim the car that was taken by mistake as a "bought" item, use familyfunds to deduct the price, and then carry on? Or sell the car and use familyfunds to deduct the proceeds? Or can I go back to the last save from before I moved, and see if I can manage to not swap cars? Or something else I haven't thought of?