I need to figure out a schedule?

Okay I work security and our schedule is all messes up. Everyone is complaining about it not being fair the thing is there is 4 officers per shift and there is 4 positions that need to be covered. Monday through Friday there is dispatch desk, patrol, visitor sign In, and patient stand by now the logical thing to do is rotate every position every two hours but the thing that throws that offf is that on the weekends we have an extra 2 officers and they do the front desk one In the main hospital and one In the pavilion....can anyone help???