You log into your acct that's connected to your pass on the app and it'll let them scan it. Each person with a pass would have to have their own phone with the app though because switching log ins will hold up the line and take longer than just giving them your card passes
I posted a link to it on an earlier thread. Its called " Disneyland". It has a blue icon with a white castle and fireworks. https://itunes.apple.com/us/app/disneyland/id1022164656?mt=8
After you download the app, you log into it, if you have already set up a Disney account. When you log in, it will show all the AP's that you have added to your account. In my case it had 2 of the 3 AP's that I have. To ad another AP to the app it has 2 choices, one is like adding a card to Apple Pay, you just scan the barcode on the back of the pass with your phones camera. The other is you can manually add the barcode # and it will show on the app.
You can choose any of the AP's on your app just by swiping left or right. Just remember, you can use the app to enter the parks but it clearly says you will need your hard ticket pass for Fast Passes and discounts.
The app also has wait times and where the characters are. Dining, restrooms and photo pass photographers. Entertainment schedules and more. It also shows a blackout calendar based on your AP. It also has your profile and lets you ad a credit card, I'm assuming for monthly payment plans.
It is cool.