oh dear what a situation this is indeed, personally i just could not put a healthy animal to sleep, just goes against everything i feel and believe in, but what to do,now that is another story, it would be sad to see them split up, and surely they would miss each other,but they may well adjust, it might be worth a try, or maybe they could just try and re-home them to someone out of the family who is willing to take them both.

I really feel for all concerned, and i sure hope a good solution is found where both kitties will stay together , i can but only wish you the very best.