As far as I gather you have a sub assembly with 2 parts in it, which is then mentioned as such in the BOM
One way I can think of is by :
- right click on the part that you don't want to see mentioned in the feature manager and select properties, in the following window you can select "exclude from bill of materials", this way only 1 will be mentioned instead of two
The other way would be to play around with the config manager on the top level.
Go to config manager (3rd tab) of the asm with the parts in it and select the top level config (default) with a right mouse click and selecting properties, this should open up some extra options for, amoungst others, the BOM. you can then select show - hide - promote.
If you select promote on the top level and then do the same for the individual parts but there selecting hide you make it so that only the ASM of the parts gets mentioned in the BOM and the individual parts get ignored while all the individual parts of the actual piping asm keeps getting mentioned.
Hope this works out for you and that it helps.
this will work for hiding any one of the componenet in the assembly but if the subbassembly has two parts and the that subassembly has sme properties means what we will do in this situation.