A SW21 switch is designed to give access to 2 satellites but DISH dosen't run a SW21 into other switches. Other switches are run into one leg of a SW21 and is only for LEGACY equipment.
i have heard that you can have a Dpp44 and Dp21 used together to get 5 sats on a single tuner, but i forget which order they were set-up. i am pretty sure it was on another topic here on this forum