Anonymous wrote:OP here with an update.
One of the two cats has completely acclimated to the family. She roams freely and will even curl up on my lap. The other one, couch-cat, we almost never see. It has been 48-hours now since we last saw him. I'm nearly certain that he is still in hiding, and i would assume that two cats are using the litter box and the food. Is this just going to be our new norm now? That there is a cat somewhere that we are feeding and cleaning up after, but we'll just never see him?
That sounds ok as long as he is eating and pooping in the correct places you'll be fine. Also maybe the other cat is keeping him company at night?