How does one make a partial atomic BOM.

Here is the situation creating the question.

We have assembly driven weldments of tanks

Multiple tank weldments are welded together

There are sub weldments that are stock existing parts that we do not want to show on the top level weldment drawing.

So Now I have a sub assembly weldment, I do want to show on a BOM, but not any of the rest of the sub welments. The BOM's are either atomic or not.

How do I make only one subweldments show it's parts for a drawings but not the rest of them?