Network of 3 schools!

3 schools… all networked by routers and frame relay w/ NT 4 Server and NT 4 workstations. These schools are in close proximity of each other and are elementary, middle and high school in a town. I would like to place 1 good quality server with backup etc. in each school. (Because of costs it is prohibitive to put 2 in each school???)The idea I have is to Put a PDC in one school and a BDC in each of the others.
Each school would log on their own users and hopefully have their own DHCP. Is this reasonable or should I just keep each school completely separate?