Since Virgin is not a *A airline the passes are not for any other airline but Virgin itself. The Velocity site on Silver membership says the passes are for "the Virgin Australia lounge". Since lounge access is pre-loaded onto your Silver membership card I doubt that the Air NZ lounge software is capable of retrieving such information and marking your entitlement as "used". You're not eligible for access AFAIK to any lounge other than a Virgin lounge - there are no reciprocal rights