that means acting member is a committee member, and will not lose this member status even after the meeting, so if this acting member attends next committee meeting, then this acting member should makes quorum. am I correct?
More or less, yes, but obviously they lose their member status as soon as the person for whom they are acting resumes their spot on the committee.
Again, I hasten to add that I’m not 100 per cent sure as I’ve never encountered this specific dispute nor seen how it was resolved. It’s a very specific and arcane situation.