The project management position is too critical for you to overlook.
Most of you have heard the statement, “You can't put 10 pounds of potatoes in a five-pound bag.” This is the best job description I've ever heard to describe what a project manager does or should be doing! Any good employee wants to be measured fairly and rewarded accordingly. You need to establish a written chain of command to define who he or she is responsible for. Then you can write a detailed scope of work (job description) that lists whatever tasks or duties he is responsible to perform.
By assigning a reasonable number of hours each week to fulfill these responsibilities, you will probably encounter that “10 pounds of potatoes in a five-pound bag” phenomenon. Keep in mind, employees should get credit for all of those responsibilities that are successfully completed on time. They must also accept the blame for any that are not.