I have two inside cats my 1st cat gave birth to 3 kittens last week. She is super friendly and is an amazing mom. My 2nd cat is pregnant as well and I can feel the kittens moving in her belly so I don't think she has that much longer. She hisses at the newborn kittens from my other cats litter, but she isn't the friendliest cat especially to other animals. My question is how will having 2 litters in one house work? Will I need to keep them seperated? Should I worry about one mom killing the others kittens? Any advice would be appreciated! Also both cats will be spayed when kittens are weaned.