I purchased 2 sets of tickets for myself, and my son for travel for one week and then for my parents for the following week on the Trenitalia website. After printing them I realised that I had mixed up the dates, obviously my own fault/stupidity. Would it be possible for my parents to travel on my tickets and I on theirs? What is the likelihood of being asked for ID. I can't change them so I would have to purchase all the tickets again unless we could use each others? The names are printed on the tickets I downloaded from the site.