What is the best way to transform an item into another?

Background

We have a component (let's call it A) which we use in our finished good and also sell it directly to the customer. For certain reasons, we have defined a separate item Ax which we sell to the customer. A and Ax are physically same. BOM of Ax only has A as phantom component. Meaning - when a work order for Ax is opened, all the components of A get added to the job automatically.

Scenario

There are cases when we make Ax on customer demands, but the demands get cancelled after we make them. We want to use these Ax now in our finished goods as A. In short, we want to convert Ax to A without any changes to costs. In my opinion, non-standard work orders are the best way to do that.