Are cats typically capable of this kind of empathy for family?

Yes, they sure have!

Cats have the same family bonds that humans have, didn't you notice? And cats can talk to each other. And even work out deals to cheat us humans. They are in many ways like us.

So that's a reason why if I would adopt cats, I'd take siblings, if possible. -- I live in the country, grew up with cats, and most of my cats are family, and it's most intrigueing to watch how they behave in comparison to us humans: You will see the exact same patterns. Which, in turn, tells me that we share a HUGE part of the same biology.

yes, it isn't at all uncommon for feral cats to share mothering duties. It is quite likely that if Bonny hadn't lost her own kittens the two litters would be mixed up and either mother would feed and look after them. It makes sense in a wild poplulation as the kittens aren't left unattended and vulnerable whilst the mother goes to hunt. It is really only likely to happen between cats that are related,

Just as some cats make bad mothers, some cats will adopt and care for any kitten in need. Foster or shelter folks are often able to save orphaned kittens if some mother cat will feed and care for them.

of course .