Controls for Radiant & FHA system

I have a 2 story colonial w/ FHA as the heat sorce on the 2nd. floor, the 1 st fl has radiant thruout w/ FHA as a supplment, both have seperate thermostats. The radiant work pretty well but on real cold days, I have to turn on the FHA system to bring the up to comfortable temps. Is there another Stat or control set up I can use to have the systems work in conjuction? Is there a way to set the Radiant for constant circulation & have the FHA kick in when the air temps drop ?
I have a Buderus 124x boiler w/ Indirect DHW tank,,each radiant zone has a seperate circulator as well as each FHA zones. Any advice would be appreciated!