Even if you get the volunteer help to fix them up and a source for needed parts other stuff. You also need to think about on going maintenance of them. If you can't provide for that, then they'll soon be in the same condition they are at this moment. Kids are hard on bikes.

You might consider just taking them to the scrap yard if the organization these belong to agree. At least then you get a little money for something else and the steel and aluminum from the bikes will be made into something else.