I have a dish 500 with 3 active receivers connected. I have three wires running from the dish into the house. There is a fourth wire coming into the house but that is for the cable modem. I want to add a 4th box. Can I just add a multiswitch to one of the incoming wires up in my attic and thereby connect the two boxes to the multiswitch? Will I be able to watch different programs on each box at the same? Thanks in advance.