I'm asking on behalf of our department that creates our manuals with composer, I'm an engineer using SW. 

She has told me that she can't see how to obtain/inherit ONLY the top level part numbers of an assembly that contains sub-assemblies. She said it always pulls the quantities from the entire model and not just the top level assembly. 

Surely there is a way to do this in composer 2018? I know in SW in the drawings we can create a BOM and in the left pane there is an option to choose all parts or top level parts.