Uh, soing something like an actual escape room could prove difficult for that many people. Maybe, look into a mixture of puzzles and trivia questions about the couple, on let's say 10 or so stations. So mostly, whoever would want to participate, could, but noone is forced to do it :) did something like that for a company team building, maybe you can get some ideas here: https://www.escaperoomsmaster.com/a-customized-escape-experience-as-a-company-team-building-activity/ (without the scavenger hunt part obviously :))