I’m happy to play along with the tooth fairy until our daughter works it out herself – or generally gets too old for it. Same for us with Father Christmas.

The kids love it at the time – and when they work it out themselves, they aren’t distraught or disappointed I’ve found – they actually feel pretty smart to have caught you out! 🙂 It’s then that you can lead into “you’ve outgrown this – and it’s something fun we do for children. Look how much you enjoyed receiving money/presents. So it’s your turn to play along for your siblings”.