Normally, the first time the ticket is used, a photo is taken and associated with that ticket. I do not recall there ever being a request for a document of any kind. Really they do not care, as long as the same person uses the ticket each day.
For you it will be helpful to write each person's name on each ticket so you know which ticket belongs to each person. It is usually recommended to snap a quick photo of each ticket in case you lose one. And I always write a cell # on the ticket in case it is lost, to improve the chance of being returned.