Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hi,
Once you redeem a Microsoft 365 Family subscription to a Microsoft account, it is permanently associated with that account and cannot be transferred to a different Microsoft account.
Since this appears to have been accidental, I recommend reaching out to Microsoft Support directly to see if they can make an exception in your case.
Click this link: https://support.microsoft.com/contactus/
Sign in to your Microsoft account.
Select Microsoft 365 > Click 'Get home support'.
Type "Chat with an agent" from the text field and press Enter.
Click "Contact support" at the bottom.
Select the product you need help with.
Follow the prompts to connect with a live agent or request a call back.