right, otherwise the ability becomes too powerful, it wouldn't require any check to acquire allies, just stick Siwar with characters with a low Cha score and auto-acquire every ally in a location deck
It would apply only to allies that were played from the character's hand, such as the one from Skull & Shackles that says "Banish this card to defeat a henchman" or something to that effect, I forget the name.
I would also think that it affects only one check, as after you play it you must discard it/recharge it. Like when you play a weapon and discard it for its power, it does not apply to both checks, only the check you discarded it for.