Picking From Racks. Help!

Hello, maybe someone can help me out on something i´ve been trying to solve for some time. I am currently running a warehouse simulation model to determine effective use of m2 and resources (forklit) for my thesis work in industrial engineering. In the model I have used an Inter Arrival option to define the arrival of 6 different functional groups (Cardboard, Oil Blends, Sugar, A, B, C), where the initial arrival from source represents the arrival of a truck, that is later sent into a spliter and split into its contents (# of pallets arrived) according to itemtype (% trigger on creation of source). Once each arrival is split into its contents and sent downstream to a Queue outside each wareouse where pallets will wait to be transported to its designated racks according to first available space. Therefore items stored in racks are using "Pallets" as a number unit (I.e. Sugar pallet stored as 1 pallet but obviously holding 1500kg of sugar, Oil blend stored as 1 pallet (or cilinder due to visual) is actually holding 808 kg of Oil Blend). Model running moreless correct to simulate the reception process of material to warehouses and sent downstream to its correct bay and level space in racks. NOW I would like to send in upstream picklist, a recipe of different items that are needed to process finished product (obviously the items on recipe are stored in warehouse), the problem is finding a way to tie production dept requirments (I.e. 10,000 kg of powdered milk in a batch) to the warehouse storage variable (all items on racks are stored as full pallets). And in the Case of ABC pallets, these are a combination of many items classified into these three groups according to how quick items rotate in warehouse.