Hey there Mariann,
Welcome to planDisney and thanks so much for your question! It looks like your visit to the Disneyland Resort is coming up in just a few weeks - how exciting!
The good news is that you don't need to stress too much about the name on the
ticket! When it comes to entering the parks, the name assigned to a ticket in the Disneyland app is really just for your own organizational purposes. When the tickets are first used to enter a park, a Cast Member will scan the ticket and take a photo of the person using it, and that's what gets associated with the ticket going forward.
That said, if you'd like to update the name to keep things organized on your end, you can
call a Cast Member at the Tickets line who should be able to help! Just keep in mind that if these are special offer tickets then there may be more details that would apply to their use - the Cast Member at the Tickets line can you let you know more about that if it applies to your situation.
One thing I'll add: if your group might be splitting up at any point during your visit, make sure your son has his ticket accessible on his own phone, whether that's through the Disneyland app or a screenshot you text him. That way he can get into the park independently if needed.
Thanks again for your question, Mariann! Your son is going to have a fantastic time.
Have a Magical Day,
Greg