Thanks for contacting planDisney with your question, Cynthia! Have no worries, or as my friends, Timon and Pumbaa like to say, "Hakuna matata!"
Although Disneyland lists their theme park tickets as non-transferable, your son's friend shouldn't have any issues using your valid admission to gain entry (I confirmed this today over the phone with Ticket Services). Once your son's friend arrives at the Disneyland Resort theme parks' turnstiles, a Cast Member will photograph him. According to
Disney's eTicket Terms & Conditions, tickets must be used by the same person on any and all days. Every time the ticket is scanned for entry, the photo pops up, and the Cast Member can verify that it's the same person using the ticket. If this is a one-day ticket, then he'll be fine; however, if you have multi-day tickets and they are partially used, he won't be able to use the remaining days.
While it's not necessary, if you'd like the name to be officially changed on the ticket prior to his visit, you'll need to contact Disneyland. The best way is via the
Disneyland Mobile app where you can directly message a Cast Member for customer support. To do this, open the Disneyland app > menu > click "Chat With Us." While a name change is not guaranteed, the Cast Member will often send you a form for a name correction. Otherwise, you can give
Disneyland Ticketing a call at (714) 781-4636.
I hope this helps, Cynthia! If you need any more advice, feel free to reach out again. Take care!
Eean