this is difficult

Think of it like a concert or an amusement park. Superset is like the general admission ticket and subset is like the VIP access or fast pass. You still get into the concert or amusement park by having general admission to enter even if you don't have VIP access to do certain things or get on rides faster. So having the VIP access/fastpass isn't necessary to be in the concert/park but you can have the exclusiveness and still be considered someone attending the venue.