wrong account

Question

I signed up for family plan under the wrong account

Answer 1

When you purchase or activate a Microsoft 365 subscription, that becomes associated to the Microsoft account used as a digital licence, and there is no native method available to move that to another Microsoft account.

The best option would be to cancel the subscription using the steps provided on this link and then take out a new subscription on the correct Microsoft account.

https://support.microsoft.com/en-us/accounts-billing/subscriptions/cancel-a-microsoft-365-subscription

Then, you should be entitled to a pro-rata refund, you can check your eligibility to a refund using the steps on this link.

https://support.microsoft.com/en-us/accounts-billing/subscriptions/how-to-get-a-refund-on-a-microsoft-subscription