I think there may be a bit of terminology problem here. It looks to me as if you are creating an assembly using the Master Modeling technique, in which you model the components as separate solid bodies in a master model (what you refer to as "skeleton") part, then use Make Components to turn them into an assembly.
If, as I read your post, the problem you are seeing is that the parts in your assembly are not Steel as your master model is, that is to be expected. The assembly components are derived from the master model, but unless they are sheet metal and linked to the master sheet metal rule, the material is not linked. The material must be assigned in the individual components, where you also assign other iProperties such as part number, description, stock number, etc. The individual components are also what you create drawings of for fabrication.
You can make this a bit less tedious by doing most of those edits in the assembly's BOM table.
My normal practice is to leave the material in my master model as Generic and make the individual solid bodies a wide variety of garish colors so they are easily distinguished while modeling. Then assign materials in individual derived parts (along with the associated appearance) so the assembly looks reasonably realistic and physical properties such as mass are properly calculated.
Hope that helps,
Sam B
Inventor Pro 2023.1.1 | Windows 10 Home 21H2
