Add additional verification phone numbers in Apple School Manager
For certain administrator and manager accounts, such as a content manager’s, you may want to add more than one verification phone number.
Note: Each phone number will get a code that must be entered to verify that specific number. Have all the phones nearby so the codes can be entered.
Go to the Apple ID website and sign in with your Managed Apple ID.
In the Security section, click Edit.
Click “Add a trusted phone number,” enter the phone number and select Text Message or Phone Call, then click Continue.
Enter the six-digit code, then click Verify.