I recently purchased an HD television and want to add it to my existing installation. I have three TVs presently set up for DTV-- two are connected to DVRs and one to a regular HD receiver. While inspecting my current setup, I noticed that I have a 4 port DTV splitter, with all four having coax attached. I don't know to which sets they run and , since I have only three sets now working, I wonder where the other coax is going. Would it work to disconnect each connection separately and see which set loses reception? Then I could use the port not connected to hook up my new tv. If, for some crazy reason, I cannot use one of the four connections, what is my next step---buy a splitter with more that 4 connections? Also, if I decide to add another DVR, do I need any special equipment to hook it up. Right now I have one SWM unit in my system. Will I need another? Thanks for any help. I know just enough about this to be dangerous.