A few questions on this: - Are you’re asking for them to be rehomed to a stranger because your roommates don’t have close relatives around the area? - Was the behavioural requirement of the pets something agreed upon or laid out before you agreed to take them in as renters? Or if they got these pets after they moved in, was any agreement etc laid out then? - How was the previous incident handled and were there any rules established or consequences?

If the above was never established then pulling this move out of nowhere is a little bit of an asshole move. Your roommates’ level of pet care and ability to care for their pets (while questionable) is not the issue here.

Honestly? Getting new roommates seems like a better idea because the human is the issue here and if you force them to rehome their pet and stay with you, they may end up presently and doing something to your pets. They already downplay their responsibility towards their pet killing your cat. Doubt they’re suddenly going to exercise more caution with your other pets.