For my children over 13, I just created
MDE accounts for them and invited them to plan with me and it was straight forward. It took me all day to figure out how to set get it to work with my under 13 son. I'll try to list the steps below as best as I can remember them. In my case, my son has his own phone and wanted to play in his own account on his own phone. This would be different if he wanted to play on my phone or in my account. I downloaded the Disney play app on his phone and created a child account. (It asked for my e-mail to grant permission). I then downloaded the MDE app on his phone and logged in as me. Using my MDE account on his phone, I bluetooth paired his magic band plus with his phone. This assumes his magic band is already linked to your MDE which ours were since we ordered through our resort reservation. If they weren't I'd assume you would need to link them to your MDE account first. Once the MB+ was paired with his phone I went back to his Disney play app on his phone and clicked on either the bounty hunter or the fab 50 game which then wanted you to link a MB+. As soon as you click on them it shows a QR code with instructions to have a parent or guardian scan them with their camera on their phone. I got stuck here for a long time until I realized that I needed to go to my MDE app on my phone and click on profile, then at the top I had to select family and friends, once there I saw his name and when I clicked on it gave me an option to click on a QR code. Once I did that it connected my son on my planning list to my son's Disney play account. It seemed to work as now when I go into his play app it has a connected MB+. I'll know more next week. I hope this helps.