Come on Lynn... you have room for more pets Maybe you can keep one and have it spayed/neutered and get it shots for rabies etc. Bella might like a playmate
BTW I don't know about Canadian possums but Texas possums are predators. A possum got into the neighbors chicken cage and had just about killed one of the birds before the neighbor got out there. I had to kill one last year that got after some very young kittens in the garage. I hated killing it but it was very persistent.