If you need more sets than the main set, you can create as many others as you want alternative sets.

These alternative sets can be used to be included in destination documents using Assembly | include sub-assembly / part. They can also be used for the creation of 2D views (using the ASSEMBLY button) of the View | main view function or to create bill of material which display only parts of an alternative set (using the ASSEMBLY button) of the Bill of material | bill of material function.