I think you might be referring to the child swap option. If your 5yo is not tall enough to ride a ride, you tell the cm and he/she will issue you a child swap pass. This will allow you to ride once, waiting in the regular ride. When you are done, your wife can use the pass to wait the short FP wait. This will not work for any attraction that your 5 yo is tall enough to ride, though. We used to love this option. But, our youngest is finally over 42", so he can technically ride just about all of the biggies.