Sorry if this is a basic question, but I did not receive good help from Dish Network support, so I am trying the interwebs 
I have a 722k DVR system with 20.0/21.0 remotes. TV2 is set-up on both our bedroom and basement tv. Currently, we just transport the 21.0 remote that we have between the 2 areas when we want to use it. However, someone gave me a 6.3 remote today that I would like to use for our basement tv. This remote has the blue tab that says UHF Pro. I called Dish and they told me it should work. They had me try to change the 6.3 remote to work on the 27 secondary remote address that the 21.0 remote is set to. When that didn't work, they tried to have me change the secondary address to 7. We could get the 6.3 remote set up on 7 but not the 21.0 remote. So, I can get both remotes to work independently, but not at the same time.
Is this possible? If so, can someone break down the steps really simple? Thanks for your help!

I have a 722k DVR system with 20.0/21.0 remotes. TV2 is set-up on both our bedroom and basement tv. Currently, we just transport the 21.0 remote that we have between the 2 areas when we want to use it. However, someone gave me a 6.3 remote today that I would like to use for our basement tv. This remote has the blue tab that says UHF Pro. I called Dish and they told me it should work. They had me try to change the 6.3 remote to work on the 27 secondary remote address that the 21.0 remote is set to. When that didn't work, they tried to have me change the secondary address to 7. We could get the 6.3 remote set up on 7 but not the 21.0 remote. So, I can get both remotes to work independently, but not at the same time.
Is this possible? If so, can someone break down the steps really simple? Thanks for your help!