You can't do what you want to do. You CAN run one multiswitch off of the outputs of another multiswitch, but in a multi-satellite set-up, you need four inputs for each multiswitch. So in your case, with an eight output existing multiswitch, four outputs (and therefore, four cables) would be needed for the downstream multiswitch. So, yes, you can put a multiswitch where your TiVo is, driven off of the existing multiswitch, but you'd need three more cables. Or you can just add one more cable straight off your existing multiswtich. Obviously, adding another multiswitch is NOT going to get you in the direction you want to go.