How do you turn regulars into advocates on social media?

A regular becomes a voice of the house if you ask for one concrete line about the dish they already order, with permission and without an agency script. Giving them an ambassador title and a compulsory hashtag turns them from a guest into someone posing. The floor points to two or three tables who already come back and have said they are willing to appear. Everyone who eats is tagged without asking and the regulars stop posting on their own. A simple agreement with each regular who accepts: which dish, which line and that the floor sees the piece before it goes out.