Makes/models of everything would help a great deal, especially considering the available connections will play a role in determining what other devices you require to facilitate your plans for audio distribution. It can be done, but I need to know makes/models to get it 100% correct, especially regarding your current stereo system. Be verbose, especially how everything is currently connected.
That said, if the main "stereo" (again, what type exactly???) is in the main viewing space (w/ DISH receiver, etc.), you could very well use a simple speaker distribution panel/amp to get this off the ground, running the wires through the attic. Crutchfield (and others) sell these. Examples of the various types of multi-room/multi-speaker connections/equipment needed:
I have 3 tv's a stereo, and a PC &phone or tablet I want to connect to the same set of speakers I want to install in the ceilings of my house. Info on the TV's is that I have Dish Network and two of the TV's work off of one receiver and the third one works off of another receiver. I could live without that third one being connected to the speaker system if I needed. All of the devices will be in different rooms. Main tv and receiver is in the living room with the stereo in the same cabinet. The tablet or phone will connect in my bedroom and a tv that works of of the receiver in the living room is there also. lastly in my office there is a tv and the pc. This tv is on a receiver that is located in my daughters room. The house is small (25x40) with easy access to the attic