would this be at all possible?

[Vince Noir]

to create an addon which could recognise if my party member's target's target wasn't the tank, and flash the frame of its target instead?

i.e. if a mage pulls aggro off a mob i'm multi tanking (as a pally), his frame would flash so i know to cast righteous defense on them via clique.

Cheers,
-Vince