She should really look into the low cost spay and neuter programs in her area. I can't imgaine how many kittens 11 unfixed cats could produce!
I bet someone will post a link to where you can look up these types of spay/neuter programs by state or something. Or if she brought any of them into resuce at least they would get fixed there. I hope you can help her find a way to get them all fixed before there are other kitty litters like the one you described found out back in her yard.
Beautiful cat in the first pic btw, and yes we can see she has lots of cats from the chair!