I have a robin's nest in my tree with four baby robins in it... and a lot of questions.?

I saw four eggs, and then four babys. This momma has been taking care of them for a week or so now. One of the babies fell out last night or this morning, and I carefully put on a hypo-allergenic plastic glove that's never been touched before and put the little guy back in there and left it alone. I am concerned that this will happen again though, and was wondering if anyone had an idea of a good way to re-enforce it. I was thinking of maybe putting a very shallow cardboard box underneath it to kind of catch the babies if they fell, I've read several places that robins wont abandon their babies because of smell, so I'm not worried about my touching the one, I'm just concerned that if I upset it too much she wont come back. I really want these birds to live, they are such a joy to watch, but there are many children and dogs around and I don't want them to hurt or kill the little birds if they fall, and I certainly don't want the fall to kill them either... any suggestions?