If there is more than one set of relay boards then there is very likely to be a board in the set they were supposed to play with the same vulnerability. If you aren't playing predealt hands, just put the cards they're playing into that board. Dealer doesn't matter, just rotate as necessary and do what you'd have done if they had played the board in the wrong orientation. If you're unlucky and there isn't a board with the right vulnerability, well, the players have just invented a new movement. Again. At least this time you know before you start scoring, and there's no need to spend half an hour in the kitchen desperately trying to work out who can still play which board against whom at what table.