I had this happen recently-had to teleport the couple from their vacation into their daughter's lot, because they couldn't come home. In return, they gave their daughter a hefty 'thank you' gift for saving them from oblivion.
Receptacle Refugee & Resident Polar Bear "Get out of my way, young'un, I'm a ninja!"
My downloads of various stuff: https://www.mediafire.com/#myfiles (including funerals!)
I tried adding them to another family then I moved them to another home but when I played again the game said they're still on vacation but when it redirects me to the vacation home they're not there anymore. I hope you find this message :<<
So you used the move in option on the cat teleporter? if not use that.
Then you may need to bulldoze the lot that is borked.
"I dream of a better tomorrow, where chickens can cross the road and not be questioned about their motives." - Unknown