Shipped items different from BOM

Say a client sells 2 products: Product A & Product B. Both have a bag of 50 nuts as part of their BOM. However, when a customer orders both Product A and Product B, the client wants to ship a bag of 100 nuts instead of 2 bags of 50 each.

From a product profitability perspective, using the BOM makes sense. However, for managing stock, ideally you want to reduce the stock of the 100 nuts bag, and leave the 50 nut bags in stock.

Any suggestions on how best to manage this scenario?

Fyi, newbie here.