I have a macro on each to do a chain heal on themselves but I usually only do this out of a fight.
/cast [target=player] chain heal

this really isn't that great during a big fight because they are all healing and nobody is doing dmg
I would suggest the splitting of the team into full dps and a part time healer.
I do this with say button 2 is full dps where the whole team does dps and button 3 is 2x dps and 1x heals ( I have a 5x team so I adjust the heals as need 4/1 or 3/2 etc )
I use the focus method of control where alts have my main as thier focus
button2:
main: /cast lightning bolt
alt1: /cast [target=focus-target,harm] lightning bolt
alt2: /cast [target=focus-target,harm] lightning bolt

button3:
main: /cast lightning bolt
alt1: /cast [target=focus-target,harm] lightning bolt
alt2: /cast [target=focus-target-target,noharm,exits] healing wave;[target=player] chain heal

then I spam between button 2 until someone needs heals then I spam button 3 and switch back and forth