Tell us all the equipment you plan to use.
For instance, with a Mercury II, you could hook up the two receivers this way:
1 to motor - with its own coax
1 directly to LNB - with its own coax
1 Receiver moves the dish and is programmed to move the dish, but the other cannot move the dish and is programmed not to move the dish. There is a place to select USALS, Diseqc 1.2, or None. This second receiver would be set to none.
This is the simplest way to do it, and it makes that one receiver subserviant to the main motorized receiver.
There may be other ways of doing this but a lot depends on the type of equipment you have.
VA 39N, 78W, SatHawk PVR8000, Mercury II, , Fortec 31", 36", 72", SG2100, DG-280, 18" Actuator, HDTV TV with no pay tv except for Netflix Streaming and Internet with Acer AspireRevo.