you might want to make a Lifetap macro... kinda harder on 4 toons for the priest to heal then all but something like

warlock

/cast Lifetap

priest

/target Warlock
/cast Renew

i only have 1 warlock in my group so this macro is easy to use and great in a longer fight. You will just have to work it out so that you can do it sequentially i suppose