"A-B" Switch to Alternate Thermostats?

Hi All, first post, not sure this is the right forum but it does involve a pellet stove so...

Will be installing a pellet stove soon for supplemental heat in the upstairs of a hi-ranch style home. The thermostat for the single-zone forced-hot-air heat is upstairs just down the hall from the stove, and I expect it to not be on much if at all while I use the stove.

But my son's bedroom and some living space is downstairs, which won't get much if any heat while the pellet stove does its job upstairs.

I'm thinking I could install a new thermostat downstairs to more accurately control the temp down there, but wire it in such a way that only one thermostat is in control at any given time, with some kind of manual switch so I can easily change which one is the "active" thermostat.

My kids are with me only half the time (divorced), plus heat and a/c are the same system, so the ability to switch the active thermostat between up- and down-stairs will be useful. Or so my thinking goes...

Wiring the new thermostat would not be a problem, it's this "A-B" switching concept I need some help with.

Any input, advice and sanity checks appreciated.

Howard

Thanks guys, I'll look into both options.