Have you put your heating on for the winter?

Pincher

Use TRVs.

Set the TRVs to maximum in the Canadians' rooms.
For the nearest radiator to the thermostat, which may or may not have a TRV, restrict the flow with the lockshield valve, so the thermostat area does not get too hot, so the thermostat is still demanding heat from the boiler. The Canadians will get maximum heat output in their rooms, while all the other rooms are at what you set the TRVs at.

Canucklehead

The majority of Canadian homes have warm air heating with mechanical ventilation and don't suffer the dampness and poor ventilation that many UK properties experience. I suggest the Canucks get slippers and jumper up..when in Rome.....;)

Canucklehead

P.S. We tick the heat on for about 15 minutes in the am but our home is super insulated and retains the warmth quite nicely....otherwise, heat on as required.