I'd add these 2 on different buttons for each mage, first one is a counterspell and focus assign macro. Press it normally it CS your leader's target, alt assigns that mages focus to the current enemy for focused sheeping.

#showtooltip Counterspell
/assist [target=focus,exists,help,nomounted] focus; party1
/stopcasting [nomod:alt/ctrl]
/cast [nomod:alt] Counterspell
/stopmacro [nomod:alt]
/a Party1
/focus [mod:alt,target=focus]

Poly Macro
This one is your standard focus poly macro with a twist, if you throw in ctrl it tosses in PoM for instant cast, Alt CS the mages focus. But most importantly it trys to polymorph every party member if they're harmful, giving you an instant button to sheep any of your party members who are mind controlled, very useful in instances...

/stopcasting [mod:ctrl/alt]
/cast [mod:ctrl] Presence of Mind
/cast [mod:alt,target=focus,harm] Counterspell; [target=focus,harm,nodead] [target=party1,harm] [target=party2,harm] [target=party3,harm] [target=party4,harm] [target=party1target] Polymorph