I took on 2 female cats who are sisters unfortunately both were pregnant 5 weeks apart the one with 5 week old kittens is jumping in the box with her sister`s newborn kittens and the other one is picking the older kittens up and trying to move them so far neither cat has harmed the other`s kittens is this normal

Often new mother cats will "share" babies and nurses each other's kids. Is either queen upset or growling? Do the kittens seem safe and cared for?

Don't allow the mothers to go outside.