You have every right to keep the cat. He need not remain stray. Make him an indoor only cat, have him tested for diseases, and then have him vacinated and neutered. The reason the resident cat cannot accept him is that he is not part of his household, just a visitor.
Your neighbor does not own...
I want to say it is a wonderful thing you are doing. I also give your husband a lot of credit. Not many men would be so agreeable about having so many cats in the house.
Just thought I would suggest spending more time with Momma Cat. She needs human interaction to become a pet. She needs...
