Transform work order costing for average costs

Summary:

Customer Nova is a high tech manufacturer and they have a concern around the impact of transform work orders on average costing.

Scenario:

In inventory they will have some new items that have either been bought or manufactured. This will normally be a low number as these are high value items.

They can receive a different item as a return from a customer which is an older model. They want to use a transform work order to transform the older model into a new item by adding and removing components.

Their concern is that the costs of the older item and any components used in the upgrade will result in the new item that is produced having a very different cost from the bought/manufactured items. This will impact their average cost, is there anyway to prevent transform work orders from impacting the average cost? They want the average cost to be the manufactured/bought average not impacted by the occasional upgrade using the transform work order