It sounds like a dangerous situation for the kittens, and mama cat as well. Maybe your daughter can offer to find them homes through your local shelter (though many people hear the word shelter, and instantly associate them with death). As the kittens get older, they will start wandering away from their mother, and the nest, and mama I'm sure isn't savvy enough to teach them that cars are dangerous. What are the chances of the babies finding homes through your area shelter? Around this time of year, calls are coming in right and left for kittens (and yes, many times for the wrong reason/Xmas) Does the shelter have a program for surrendering kittens, and getting the mom cat spayed in exchange for the kittens? This would be a great incentive for the folks, especially if they are unable to afford spaying fees. I know you'll feel better knowing that you had a part in assuring a good future for the kittens, as opposed to finding them dead in the street. Be brave, and us PTers will help you through it the best we can. And keep us posted please. I'm known to make entire families of kitties go "POOF" into the night, and I don't regret it one bit!