I work for a small hospital clinc in Montana. For the last few years our 3 nurses and office staff have voluntarily worked thru the lunch hour. We eat when we can at our desks. This is the way we like our office to run and don't want to change. The administration wants our nurses to take the 1/2 hour lunch break. Can the sdministration force the nurses to do this?

Yes, they can require a lunch. If an employee refuses, they can subject themselves to disciplinary action, up to and including termination, as the refusal can be seen as insubordination.