I do feel badly for the kitties
and for the girl who has to rehome her babies because of idiotic family members.
However, on the other side of the coin, she is doing the responsible thing. I'm sure that it's not easy for her to post that ad, let alone give up her kitties. But she loves them so much that she is willing to let them go to a safer environment for them where they will be loved and cared for by everyone.
But I agree. If her in-laws are living with her, then she should be giving them the boot. However, it could be that she is living with the in-laws, and that isn't an option.