Add Material to job, and then bill additional cost on AR invoice

It would be really handy to have a way to add a part to an existing job, mark it as added, and have it show up on the AR invoicing as a separate line.
The box “Added Material” seems to claim this is what SHOULD happen, But it doesn’t.

[(from the Help Browser, Field help)
Added Material
When selected, this check box indicates that this material was added after the initial setup of the job. The option lets you track material changes on the job; this material will be listed as an added material within the AP Invoice Entry program.] ap? seems like a typo?

We have to do this all the time. Add a bracket or a cable that needs to get billed to the customer but really needs to also be tied to that job number. Am I missing a check box or setting with this feature?