MRP run to combine pr's for particular component on monthly basis (project)

Hi, wants mrp run to combine the qty of same component which is the bom item for different sales orders (project orders). also required to know the qty tracebility against sales order or project order. for that we maintained MB lot size and 1 in ICI in mrp4 view of the component material master. wants system to combine the qty of same component and generate 1 pr (purchase requisation) on monthly basis. please advise any user exit or badis or development is possible.