The remaining negative cats should be checked every 3 - 6 months, and if positive, be removed from the house. (lbah.com)
FIV positive cats can be co-housed with FIV negative cats provided they live in a «stable» environment where the cats do not fight with each other or create puncture wounds which may transmit the disease. (bensalemveterinaryhospital.com)
An FIV - positive cat can live with an FIV - negative cat as long as neither cat is a fighter, or if the FIV - positive cat has no teeth. (bestfriends.org)