Hey there Dennis,
Welcome to planDisney and thank you for your question! It sounds like you're planning a trip to the Happiest Place on Earth soon - how exciting!
You can absolutely purchase
theme park tickets for others in your group and keep track of them all on your
Disneyland Resort mobile app. In fact, this is typically my role on trips with my family! Functionally, this would work just like how I manage tickets for my wife and kids since I am usually designated the official holder of the tickets!
The main thing to keep in mind here is that each ticket will be assigned to a specific party member when you first enter a park. The Cast Member at the entry gate will take a picture of each Guest which will then be associated with their ticket for its duration, so it will be important to keep track of which ticket belongs to each member of your party.
If there are other people in your group who want to help keep manage your group's tickets, you can link some or all of the tickets with them in their Disneyland Resort mobile app. Just click on the menu button (the three horizontal lines), select "My Tickets & Passes," then "Link Tickets & Passes." From here you can scan the ticket barcodes with your phone camera or manually enter the Ticket ID. This can be helpful if your group is going to split up during your stay.
Thanks again for your question, Dennis! I hope you enjoy your upcoming trip to the Disneyland Resort.
Have a Magical Day,
Greg