My boiler has a 6 zone taco panel all being used. I have a stump for zone 7 roughed in. I have all the components to build zone 7 and add another zone but with the current Taco relays all being used I bought a single Taco relay I will add for the new zone. I'll need to tap into the power going to the boiler and the wiring sending the firing single to the burner. My plan is to tap into the power for the second taco relay at the switch and then splice and pigtail power for the burner to both Taco panels. If there is a problem with my plan I'm hoping someone with more experience can chime in, or if there is a better way to do it I am open to that too.