I think you're both on the same page but there's a slight miscommunication

"There isn't something for your slaves to focus the target of the current window" -- Toned is correct in pointing out that you can /focus the "target of the current window". The Quick Setup 38 macro set (from the Quick Setup Wizard in ISBoxer 38) includes this gem:
Code:
/clearfocus
/focus {FTL}
/focus [@focustarget]
It should work fine given a proper Key Combination (it doesn't have one assigned by default)

And Ualaa is correct in responding that nobody but Toon A can determine Toon A's Focus Target. The quote just didn't say Focus Target.