Unless you have somewhere to place the kittens I would suggest to trap mom cat and abort the kittens. Then release mom and continue to feed and provide for her. I know most of you do not approve or like this option, but this is what we do to manage our feral colony. This way you don’t have kittens living a feral life, and mom cat does not have to be destroyed. Now if we have homes for the kittens we will trap and foster mom until kittens are ready for their new home, then have mom spayed, and release her and continue to care for her.