It is highly unlikely that three people will be watching three different stations, unless you have a large Family of five or more. Children are generaly the reason many receivers are added, and at a cost of $4.99 for each additional, can cost up to $20.00 extra (four in addition to the primary). Dish Network currently limits all households to a maximum of five independent receivers.
Using the Coax output of one or two of the receivers allows you to distribute the signal, via coax cable, to other televisions in the household. Pre-existing cable from your old digital cable, or standard analog cable, can be used to distribute the signals to the appropriate sets. Installation is relatively easy, and cost effective.
By using an Infrared-to-UHF-to-Infrared kit, allows you to change the channels on the television associated with the television on that coax cable run. You can also order receivers with UHF remote options to allow the same viewing.
You also have the RCA type output jacks that can be used with an in-house distribution system, or 2.4Ghz broadcast system from room-to-room.
This will cut costs of adding separate receivers,
and allow for more controlled viewing by young children, and
teens.
I have also known Truck Drivers to do the same thing
by having a spare dish on their rig somewhere. Their home programming
has two receivers, so they take one with them on the road when they go
on long trips.