Now, having a thermostat directly over heating pipes isn't a great idea to begin with. Having the thermostat directly over a baseboard that is controlled by a different thermostat is downright ridiculous. The problems really arise when the heat in our bedroom needs to turn on, as it heats the thermostat to the dining room so that zone does not turn on. As I noted earlier, that zone includes the bathroom, so that can lead to some chilly mornings in the bathroom.
To deal with this issue, we've had the thermostat in the dining room set well higher (74-75 degrees--higher if its really cold outside) just so it will come on. The technicians who have serviced our boiler have not had any real suggestions and have said that moving the thermostat would not be an easy process. Thankfully, modern technology has stepped up.
We purchased a Google-Nest thermostat and a couple of wireless sensors to go with it. I placed one sensor at the other end of the dining room and another one in the bathroom--both well away from the baseboards or other heat sources. While the thermostat is still in the same place, it uses the readings from the temperature sensors to determine when it needs to go on. It also sends that information (and the controls) to an app on my phone.
The process took a good part of my day, but that was mostly due to a defective unit. Once I returned it and picked up a new one, everything connected. The system seems to be running smoothly now. We purchased the higher-end "learning" thermostat (they were sold out of the less expensive one--at least, after I returned the defective one I first purchased). It claims that its efficiency will make up for the higher cost in a year or two. We will have to see.
I'm just excited that we have it basing its activity off the correct temperature now.