It would be nice to have an option in the idw where I could list ALL parts reguardless of level in a single, non-structured, parts list. If I have one top level and 30 sub-level assemblies with one 3" elbow in each of them, I want one line that says I need thirty 3" elbows. Currenty, I have to place a structured parts list, expand all the sub-levels and export to excel and combine the parts from the sub-levels to give to purchasing. This open up potential for math errors, etc that Inventor would handle automatically. All I want to know is how many 3" elbows are in my whole machine. I still need the structured for drawings and stuff, but purchasing wants all parts in one list. They don't want to look in 5 different spots for 3" elbows. When we used to run the pipe in the top level as 300+ individual fttings it was not too big of a problem (but took a long time to model), but we started using the Tube and Pipe feature which save tons of time modeling but making a list when from 20 minutes in Inventor to 2 hours in excel. And excel doesn't update too well when I make a change to the model.
I'm pretty sure you can do what you are asking, have you looked at the "Parts Only Option" for you materials/parts lists?
This is currently available functionality in Inventor. I would recommend placing a "parts only" parts list on another special sheet or off page for use by your purchasing department.