The most appropriate action by the master scheduler is to forward the request to senior management. According to the Time Fence Control (MRP and Supply Chain Planning Help) - Oracle, the demand time fence is a period within which the planning process does not consider forecast demand when calculating actual demand, and the planning time fence is a period within which the planning process does not alter the current material plan or master schedule. The master scheduler can make changes to the master schedule within the planning time fence, but only with approval from senior management. The request from marketing falls between the demand and the planning time fences, which means that it may affect the current material plan or master schedule, as well as the capacity and resource requirements of the production system. Therefore, the master scheduler should forward the request to senior management, who can evaluate the impact and feasibility of the request, and decide whether to approve or reject it.