I do some TNR, and three weeks ago I had 8 ferals living in my garage. The critical thing to do is to have them humanely trapped and altered as soon as practical. Otherwise you will have a pack of cats on your hands in no time flat. I can point you in a direction if you are interested in being pointed.

Clover, it isn't necessary to euthanasize healthy, feral cats. You cannot successfully eradicate feral cats. There is a theory called the vacuum effect that will move new cats into the area. TNR is the only humane and practical solution here in the US.