Discussions

I have a question that I am hoping someone has the answer to.  
 
We had a trio of cats living in our shed for quite some time. No idea where they came from. We set up a warm place for them and when it became apparent that they weren't going to go back to wherever they came from, we brought them inside. One cat was very pregnant. We took the other two to the vet and fixed the male but the other female also was pregnant so we couldn't spay her.  
 
Cat #1 gave birth a couple of weeks ago to four kittens. All healthy and she is a good mommy. Cat #2 woke me up during the night last night because she was in labor. She also gave birth to four kittens. One kitten did not survive and she will not care for the others. She totally freaked out giving birth and wouldn't stay still. She ran all over the house, giving birth in different places and did not go back to clean or remove the sac from her babies. Once we realized she wasn't going to do anything, we cleaned them. She will not feed them. However, Cat #1 has now stepped in and added these babies to her litter. She cleans them and feeds them. It was either let her do this or let them all die.  
 
Is it okay for an already nursing cat to do this?