I have a Dish 5000 that I use only for HBO. I have several other TVs in my house that use AT&T cable. I do not want to put Dish receivers in every room, but would like to (on rare occasions) pipe the output of the Dish 5000 to other TVs in the house. I cannot run any additional cable, so need to use the cable already in the house. My Dish 5000 happens to sit very close to the place where the cable comes into the house. So, is there a way to combine the Channel 3 output of my Dish 5000 with the Cable signal from AT&T? There is a channel 3 on the cable system, but I do not care for it. I am assuming the solution would involve somehow blocking out the channel 3 from the cable system, and then combining with the channel 3 from my Dish 5000. But I have never seen any accessories that do this "strip then combine" trick. Any thoughts??