Slaving a receiver usually means that you can use the loop out of a receiver to allow another receiver to watch programs too. You can also use high frequency splitters. The drawback is the "slaved" unit can only see the same polarity as the main unit.
There are 3 ways people usually slave units.
1. They have a big dish and a 4DTV or analog box. They also have a LNB which has 3 wires to control polarity. They want to add a DVB/FTA box to the mix. So they hook it up like such.
Add a receiver
The 4DTV controls everything including polarity. The DVB box just follows along. When they blind scan, they scan one polarity, then flip the polarity on the 4DTV/analog box and rescan the other polarity.
2. You have a motorized KU only setup with a LNBF (most of the LNB's out there today). They want to add analog to an existing DVB setup. They use the loop out on the DVB box (Pansat, Coolsat, Fortec, etc) to the analog box. The DVB box does all the work and the analog box just follows along...This is how I have my setup
LNBF----motor-------------Coolsat 5000---loop out to Toshiba analog box
The CS5000 controls everything. The analog box gets whatever polarity the CS is set to
3. Option 3 is someone who has a big dish and actuator but uses a LNBF. There are two ways to do this. Either get a VBox II to allow your DVB box to control the big dish motor and slave the analog box as done in option 2. Or you could set it up as option 2 but the actuator is still controlled by the big dish. This eliminates one piece of equipment (VBox) but it is a 2 step process. You would use the analog box to move the dish to the satellite but the DVB box can get both polarity at once.
Hope this helps...or convolutes it even more