Well -- It depends!
I wouldn't have a zone connected to the coal boiler aquastat. I would connect the T1 and T2 on the coal boiler aquastat with a jumper and let the boiler idle fire as it needs --- and react (hi fire) to energy draw as the building requires.
I would wire each t-stat to its zone pump via the relay of course to control energy flow out to the zones as its called for.
But I am simply a figment of the public internet - Your mileage may vary.
I would also have an outdoor reset wired in place of the jumper I describe above to command the boiler temperature to degree day load.
Then there is that pesky Balancing of the flow out to the zones
- but lets get the house heating wiring corrected first.