Mama cat in relation to baby cats+

Question
Mama cat had a litter in our yard, weaned them and left. We adopted the kittens and they live in our shed in the back yard, but they are starting to act like house cats (some). We feed them, brought them toys and a scratching pole.  Now the Mama cat comes back after another litter and wants to eat. She hisses and growls at Socs (male) and Tiger Lily (female). Lately she's been fighting with them. What's happening?

Answer
Hi
You didn't say if the mama cat is your or if she is a stray. I think the real problem here is that fact that without neutering the cats you are going to get up with many many mouths to feed and lots of territorial aggression.
The reason why the poor female cat is acting aggressively towards her old litter is because she now has another litter of kittens to look after and she is telling the other kittens to be independent and to find their own territory. This will get worse as more and more cats come into one area. Female cats have to be most loyal to their youngest litter, they won't be sentimental about her other kittens.
If the female cat is a stray perhaps you should consider having her spayed anyway, that way the cats that are already in your shed will be able to stay in this territory (you will have to have them spayed as well as from 6 months old they can start to breed. See if there is any animal shelters in the area that will help with rehoming some of the kittens or help with spaying costs.

Kate