Windows 10: how do I find out if my email address is an alias for a microsoft 365 work or school account

how do I find out if an email address is an alias for a microsoft 365 work or school account ?We'd like to add our daughter to our family office 365 subscription, with the email address that she uses most often. But when she currently uses word or excel on her macbook, she is already logged in to microsoft using that email address. She doesn't know how, and nobody in our house seems to be paying for a microsoft account using that email address. How would we find out if this email address is setup as an 'alias' for an another microsoft account such as a previous employer, or school. She'd re

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Microsoft account email alias problem

i changed the alias and removed the default one, so now i have only the new one in the list...the default one that was their is gone

i did not know that removing the default alias would mean i would lose my original email address, because now my original email adress isnt working.

and on top of that, my new alias or should i say new email address isint recieving emails... over 20 years of usuing the same email address and its gone because i thought a alias was just a display name.

 

Microsoft Account alias change

Trying to change the primary alias on my Microsoft account. As per instructions I go to "Add an alias". I choose "Add an existing email..." I insert my newly purchased domain and O365 account email *** Email address is removed for privacy ***. I am rejected with the message "You can't
add a work or school email address as an alias to a personal Microsoft account. Please try another." This is not a school or work alias. It is my my new personal home domain now.

 

Adding or changing an account email address

I have followed the recommended process for adding an alias email address as a step towards towards changing the email address associated with my Microsoft account from old to new. However,
whenever I try to enter my new personal address the response is "You can't add a work or school/university email address as an alias to a personal Microsoft account. Please try another." Why is this and how can I complete this action?