Production Order Customization to Limit Qty in Document

I have a client who wants us to come up with some customizations on the Production Order screen to take into consideration the fact that the company can only produce 1,000 gal of something at a time. For example, if MRP recommends 4,876 gal of a product be produced, the result would be 4 production orders for 1,000 gal each and another production order for the remaining 876 gal (they can only produce 1,000 gal at a time). Obviously with current SAP functionality, one production order for 4,876 gal results from an MRP run.

Has anyone ever had experience with a scenario such as this or do you have any ideas for how we can make this work in SAP B1 for our client?