x2
If cannot find her, you could combine with a queen excluder and give the bees time to sort it out. They will keep which of the two queens they like and dispatch the other (if there is another). It would take a week or so for that to happen. Then you could go back and remove the excluder.
However, the better decision may be as you say -take the loss- Let them run the course. You will either end up with a weak queenrite hive or old laying worker hive to shake out later.
All three scenarios are equally probable outcomes ..