Tutorial: Adding sub-assembly parts to an assembly parts list
This tutorial will step through how to add sub-assembly parts to an assembly drawings part list in Inventor
Special Thanks to William for letting me use one of his assemblies for this Tutorial.
Answered with a tutorial: https://grabcad.com/tutorials/tutorial-adding-sub-assembly-parts-to-an-assembly-parts-list
I don't think you have to delete the parts list and balloons as in Step 2, rather change the BOM in the assembly--the drawing BOM should then update with the sub assembly components. It is only necessary if you are trying to get the "parts only" BOM, rather than it showing sub-assembly 3 with parts 3.1, 3.2 etc.
There are also some BOM scripts out there that can be used to number global BOM parts, so sub assembly #3 parts would start out at 3.1 on their respective drawing sheet (rather than each sub assembly starting out at 1.) Sometimes this is handy when you have large assemblies and each sub assembly (and all of it's parts) retain the same BOM number as on the main assembly BOM.