Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
When you upgrade form the Microsoft 365 Personal subscription to the Family version, you are charged for a full new subscription and the remaining time on the Personal subscription should be converted to the Family subscription on a pro-rata percentage basis of 92%, if you log into your Microsoft account (https://account.microsoft.com/services/) and check the expiry date on your new Family subscription is it not indicated that has happened?