Rank Seperation Pay

As a reasonably new chief in a department that has senior firefighters being paid as much or a little more that my young officers, I find that hard to manage. My newer officers question theirselves why they took on so much more responsibility and work when receiving less pay than that of a firefighter rank. I am gathering and preparing for this to be addressed as a priority in my upcoming budget. Any and all help would be welcomed. Also, the reason for the senior fighter being paid more is that the City has a step raise scale, which has helped bring about the situation.