Multi-supplier in MRP

Hi,

When we Run MRP, system suggest OP (Purchase order) messages to a supplier (supplier number will get defaulted from item branch), if there is no supplier number mentioned in item branch system will ask user to update supplier number at the time of Processing OP messages. My question is when there is multiple supplier for the same item how to configure and also is there any standard way to split the total OP messages based on the supplier split (20% to one supplier, 40% to next supplier and 40% to remaining supplier)