The person with the restaurant reservation is my accomplice.
Georgetown’s Harborwalk follows the Sampit River behind the Front Street restaurants and shops. If the couple is taking a walk there before dinner, give me the name on the private-room reservation. I can be inside and ready by the time they return, with no need for a nervous cousin to explain why a man in a suit is following them along the waterfront.
Give each partner half the trick.
One decides which card we use. The other decides who holds it. Neither has to give a speech, remember a date under pressure, or tell the table the detail of the proposal they’ve successfully kept private for decades. Tell me whether they’d enjoy helping or would rather volunteer their friends. Either choice makes the celebration about them.
If you have the room through coffee, clear one end of the table for a seated reveal after the toast. If the restaurant needs it back after the last course, I can work a station during drinks instead. Ask the person running dinner which fits their service; the person setting down hot plates should always have the deciding vote.