I can’t invite Family Sharing why

I admit I am confused. It says your ID is already in a Family group but then why is it saying you need to be asked to join the other group?

Have you tried leaving the other group? Leave Family Sharing - Apple Support

Refer to this document for ways to contact Apple ➞ Choose your country or region - Official Apple Support

Select your country (also look for "other" regions), then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service by telephone ➞ Contact Apple for support and service - Apple Support

By the way, you can only be in one family group at a time.