Setup Suggestions For Built In Speakers Throughout The House

(First post, an audiophile friend sent me this way.)

I just bought a house that came with some built-in speakers throughput and am looking for suggestions on what equipment I should get to create multiple dynamic zones.

Details: There are currently 4 pairs of speakers:
1. Two in-ceiling in the living room.
2. Two in-ceiling in the dining room (with volume control knob).
3. Two outdoor speakers in the backyard.
4. Two in-ceiling in the master bedroom (with volume control knob).

All four pairs are independently wired and the wires terminate in an area that has plenty of room and ventilation for equipment, if needed.

What I'm hoping to achieve is a setup where I can dynamically direct the individual speaker pairs across up to three independent zones playing different audio.

For example, I can imagine a situation where I want
Zone A: pairs #1 and #2
Zone B: pair #3
Zone C: pair #4

Or, maybe
Zone A: pair #1, #2
Zone B: pair #3
(#4 off)

But also of course
Zone A: pairs #1, #2, #3, #4

And so on, and so on.

The audio source for all of these zones would very likely be streaming (Spotify, Chromecast, etc).

So, hivemind, is it possible to make this vision come to life? I'm a software engineer by day so am not averse to doing some Android development or utilizing a Raspberry Pi type device to control switches, for example. I have a decent understanding of audio equipment and terminology, although admittedly haven't played around with anything more advanced than a receiver/amp+5.1 speaker setup in ~20 years.

Lambsdread, your problem is wanting to play different programs in each location. The only way to do this is by having a separate system in each location with line levels coming from the main system. Then you would have the choice of playing whatever you want locally or what is on the main system. Unfortunately, you only have speaker level wiring to your main location. This is the problem with installed systems like this. They become out dated as soon as they are installed. The modern way of doing this is by having wireless loudspeakers in locations you want sound then you can stream individual programs in each location. You could use a Sonos connect-amp on each set of speakers from the main location and control the whole thing through your wireless network. You would have to buy several connect-amps but that is not insurmountable. This is the only solution I can think of that would work.
Thanks for the reply, mijostyn.

Ya, now that I think about it more, I guess I was hoping I would stumble across an open/programmable version of something like Sonos. Sonos is great but also pretty pricy, $600/amp is high enough to convince me that perhaps this idea of mine is, unnecessary :).

I haven't given up yet, though. I've been randomly Googling around for terms like "programmable audio switch" and coming across equipment like this:

I'll update this thread if I make any progress.