I just got a new Honeywell TH8321 Stat. The old stat jut used the R jumper for the Rc and had the G/Y tied as one. I would like to use both xmr's and hook the yellow and green to their position on the stat. The furnace has no green terminal. The stat has R/h and R/c but one common screw. Both the The package a/c and the furnace has a blue. The stat uses the furnace blue to operate. I know the Rh and R/c are separated. Can the commons from both be tied together ? It there any problems that might arise from using two xmr's ? Thanks and God bless.