Change to serial control with on hand and open sales orders

We are looking to roll out predefined serial control which is unique within inventory model and items to a greater population of final product. The issue in front of us is that we have inventory on hand for these items and in flight sales orders. Is there anyway of making this change without having to transact all the items out of inventory and then transacting them back in? Because of the uniqueness within the model and item we potentially have hundreds of individual items within a product family.

Any thoughts would be greatly appreciated.