So, I’ve been using macros for more than a year now and I notice that not many macro’s use the target.Focus Command for Instances/Raids, I was wondering how come and if there is a pretty easy way to get the macro to target only what the focussed player does (Eg, I focus the tank, I only attack what the tank is attacking), I am sorry if this doesn’t make much sense, I am one of the people who use this because I have a disability… 
)
Not sure if this still works but I used to use
/assist focus for arena in burning crusade using the in game blizzard UI macro, try replacing the the line in key press "/tar enemy [nodead] with /assist focus after making the tank your focus target