From all I’ve read, it’s the title of a position at one of the resale companies, other resale companies call them account administrators or the like. It’s basically the person who keeps buyers/sellers advised of progress on already sold but not yet closed contracts & fields their questions so the salesmen/agents don’t have to.
I always chuckle when I read about the so called concierge service, because that resale company recommends a closing company that usually takes 3 to 4 times longer than other title companies to generate closing docs after ROFR, which to me is the antithesis of a concierge experience

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OP, you might verify w/ your ‘concierge’ that the buyers know the sale can close before the closing date. Most real estate (like buying/selling a house) closes on the exact date the contract says it’ll close for tax, mortgage interest, & liability reasons, a new to
DVC resale buyer may not realize that DVC isn’t like that & that the deal usually ‘closes‘ before the date set forth in the contract.