The built in Ecobee thermostat app certainly lets you do Auto,Heat,Cool,Off and provides temperature and temperature settings. And also operating state.
Given those values and controls, you could turn off two at a time with rule machine logic.
You definitely could.... That said, note that no home automation hub is 100% reliable. Make sure you have a backup plan to protect your home if it accidentally turns all 3 off, or turns one off and fails to turn it back on again.
AKA - Don't come here and complain if it messes up and your pipes freeze.
EDIT: In that regard it would likely be "safer" to have logic that drops the set points on the 2 not running thermostats down to ensure they don't kick on, rather than turning them from heating to off. Then if the logic malfunctions the heat will still turn on at some point - may be cold/low temperature but you would still get heat.