Hi there, Alexis, and welcome to planDisney!
Thanks for submitting your question to us. How cool that your entire family are Magic Key Holders! It's always nice to see another one of us here and I hope you've been enjoying the benefits that come along with your
Magic Key Pass.
How gracious of your Mom to want to take your children to The Happiest Place on Earth! Although your idea would probably be fine, I have sometimes had Cast Members ask to see the actual ticket within the App as opposed to a screenshot. My best recommendation would be to actually link their Magic Key Passes to your Mom's MyDisney account so she will have access to all the Passes on her
Disneyland Mobile App. That way, she'll be able to effortlessly swipe across to access all the tickets to show the Cast Member.
To link your children's Magic Key Passes, have your Mom open the Disneyland Mobile App on her phone and go to the "≡" Features Menu. Scroll down until you see the button to "Link to Account." Press that and on the next screen, she'll use her phone's camera to scan the bar codes from each of your kids' Magic Keys (or manually enter the ticket ID number).
Alexis, I wish your Mom and your kids the most magical visit to the Disneyland Resort! Please feel free to write back to us if you think of any more questions. You're always welcome at planDisney!
Wishing You a Great, Big, Beautiful Tomorrow!
-Al