I'm building a media room in my house, and have 4 TV's (one HD, 3 standard) arrayed one wall. I've ordered Directv receivers (DVRs) for the three standard def tvs, and an HD receiver. How can I use the remote controls to control them individually? I expect a remote for any one of the three DVRs to change the channel on all three DVRs, which of course I don't want. Any suggestions?