If you are coordinating dining and Fast Passes across more than one account, it's important to link the My Disney Experience accounts. This ensures you can coordinate your Fast Passes. Here's a photo tutorial on how to do it in the Android App:
After your open the App, Click in Mickey to see all your options. Then Click on Family & Friends:
Inside Family & Friends, you will have the option to Add a New Friend:
Next Click "Enter a Guest's Name":
Then you will enter the information including first name, last name, birth date (if you know it) and if they are 18+ or their age if they are under 18.
Scroll down a little more and you will see "Invite to Plan and Share". It's very important that invite the person to plan and share. This is how you will link your accounts. If you don't click this, then you have just created an imaginary account named after your friend. Your friend won't be able to see your account and you won't be able to plan Fast Passes together.
Then you enter in the email address that the person uses for their My Disney Experience account:
Click Send Invitation and you are on your way to linking your accounts. Your friend will then need to accept your invitation.