HOW TO SHOW A SPECIFIC COMPONENT OF A SUB-ASSY IN THE BOM TABLE OF MAIN ASSY

Hi,

Is there a way by which we can show a Specific component of a Sub-Assy in the BOM TABLE of the Main Assy??
I am aware that this can be done through Flat and Recursive Option, but I am wondering if this can be done through the use of Relations/ Rules so that the manual work can be eliminated. The Pipe part number is unique.

Example:

The Main ASSY below is made of Sub-Assy1 and Sub-Assy2.

I would like to show the Pipe in the BOM table of Main Assy. so the Idea is to include all the pipes in the Bom table of main assy if they are ever used in any of the sub assemblies.

Final BOM table:

Thanks,

Deepak