She reminds me of the feral at the shelter. It's that look in her eye and it's a very dangerous one!! The calico at the shelter has finally calmed down enough that you can put your hand in her cage and remove the babies but DON'T EVEN THINK ABOUT TOUCHING HER!! It will get better and I have no doubt that your mamma cat will come around quicker and easier than if she were in a shelter.
Your mamma kitty doesn't know what she has come up against! She will be really surprised to learn that humans aren't so bad! Good luck and I have no doubt that soon we will be hearing good results. Please keep us posted.

btw-she is very pretty!