I have a three zone hot water boiler based heating system. The boiler is currently at one end of my ranch style house. The radiators appear to be directionless (no valves or anything). One of the zones covers approximately half my house and it goes LR/DR->Family Room->Master BR then back to the boiler. The MBR is already a cold room for a multitude of reasons (above garage, low radiator to room size ratio and 2 exterior walls) and we are never in the LR/DR but in the current setup it is always significantly warmer than the Family Room (room we are in the most and the location of the thermostat) and Master BR.
Would it be possible to drain the zone and reverse the in/out pipes so the flow reverses to MBR-> FR ->LR/DR?
I feel like this would work better than using remote sensors with a smart thermostat (I am installing an ecobee anyway for easier control) because the remote sensors would just force the heat on more to make the Family Room and MBR more comfortable while the LR/DR would be sweltering and wasteful.
Below I added a picture of the current valve setup, piping example and the input side of the boiler. I definitely have a single loop setup and I realized the zone goes LR/DR->MBR->FR (or so I hope).
I think I may follow some of the advice and just add a new zone and split the LR/DR off. I need to do some digging because the MBR is over the garage and the pipes are inaccessible without tearing out the garage ceiling but as long as I can find where the pipe goes I can splice it.