I was down to one family member in one of my generations and suddenly I had two collectibles pop at once, a common and a rare. I had dropped my person on the common one before I saw the rare but immediately picked her up to drop her on the rare one. I noticed my money total increase by $5 when I picked her up and the collectible poofed.

I tried it again a couple of times, and sure enough, you make the money on the collectibles even if they never make it back to the office. Sure does save a lot of time waiting for them to walk around, especially when they're old and slow.