I've actually seen FC1 several times this week next door - for one reason or another. She always reacts very gratifyingly by getting onto my lap and kneading and purring. I also went to the vet with her (and her new cat father) yesterday for her final wound check. Despite having refused to stay still, not climb, not jump and not wearing her collar or surgical jacket, it has healed perfectly - phew.
Anyway, I'm glad that she isn't dark with me for taking her to new home and abandoning her! I think it really helped that she had spent lots of time with her new owner and she knew he was a safe person. Also having all of her things with her (toys, but also her blanket, her food bowls, etc.) must have been reassuring.
FC2 is very loving, and I think his biting reputation was very undeserved. I do keep waking up to him washing my hair, which I suppose some people might not like 😂