Copy with Mates

Hey everyone, I'm new to Solid Works (i'm a student) and new here, so forgive me if this is a dumb question, but I just can't figure it out.

In my assembly, I have several parts mated together. In this case, it's a wheel/tire/axle assembly. What I would like to to do is just highlight all the relevant parts, copy them,  and paste them elsewhere so that now I have 2 sets of assembled wheel/tire/axles, later to be joined by the truck body. When I select the parts and right click - "copy with mates" it says "the selected parts have no mates" even though the wheel is mated to the tire, and the wheel is also mated to the axle. So it won't let me copy and paste multiple parts.

I understand that a good solution would be to make a subassembly that contains a wheel/tire/axle and then just insert that. But I would really like to just duplicate multiple parts and mates in place.

Any ideas?

Thanks very much in advance.

SolidworksAssemblies