Maybe by using the "welded construction" tool, and from there, come out the welded part bill of materials (which takes into account the bodies of the part)?
Here is my research on the solution you propose, I have circled in red what I have to extract in nomenclature without going through the custom pp because the basic components are extracted from the library.
In your SLDPRT, obligation to have a list of welded parts, so a welded construction because several bodies. In your SLDDRW, insert a normal bill of materials with "Detailed list of welded parts" and "detailed bill of materials" options.
In this way you get 1 - Name of the set that corresponds to the $prp of the SLDPRT 1.1 - Name of body 1 which corresponds to the $prp of the mechanically welded body 1.2 - Name of body 2 which corresponds to the $prp of the part inserted in SLDPRT 1.
Another thing, part 1.2 so the axis is a part within a part, when inserting it you have to tell it to copy the properties in the list of welded parts.