BOM SALES QUANTITY RESTRICTION FOR CUSTOMER

Dear Expert,

We use Bom sales to Promote for Customer. Follow our blueprint, we allocate a quantity of product to customer depend on Sale Promotions. In SAP standard i know that we can set Expire date for BOM sales but how can i set the limit quantity for BOM sales? Example we just want to sell a fixed quantity of products in a period for a Customer Group. If Saleman want to sell more, they have to release to extense by Approver

Is there a workaround for this requirement?

Many thanks,

Chinh