Please re-read what I wrote as you misinterpreted what I said: I said to take up the vet's offer of getting her cat a tranquilizer for a FEW DAYS to see if it makes a difference. That's what they did with my cat, she was on a tranquilizer for a FEW DAYS, then she was all better, and she takes it now when needed. So, I DID NOT say for the cat to be medicated LONG TERM at all, I wouldn't be for something like that. And, if the source is indeed stress, medicating will not be covering the problem, it will be helping it. A tranquilizer calms the nerves and reduces stress, and if stress is the source of the problem, it should help, like in my experience.The reason why I posed that question to you is because of your comment "please don't give up until you find the source and change it". The OP stated that her cat started spraying after her first child was born, so that tells me that, more than likely, he is marking his territory. If that is the case, how can the source be changed? I repeat, what then? Surely finding him a loving home (where he wouldn't have to be medicated) would be a kind thing to do? (I would imagine that medicating him will only cover the problem, not solve it and certainly not be good for his long term health). I'm not quite sure how you know, without question, that the cat "isn't deciding to spray, the poor little guy can't help it"?? Whether he can help it or not, the result is still the same: a very unhealthy environment for all concerned.
Can I ask, what was the source of your cat's stress?
And I am not a veteranarian, I can't answer all of your questions. All I am doing is offering hope and positive vibes for the OP and her cat. I am offering my advice based on positive experience in hopes that it would help her kitty.
OP: I know you love your cat, so I would really try ALL options before having to consider rehoming your cat. If you do indeed decide to rehome your kitty, find someone you know and trust, of course. But the next step that I would do is ask your vet about prescribing acepromazine(or something like it) for your kitty like I described earlier. Please keep us updated!