Can a person be part of 2 family sharing groups?

Do you mean the child has two IDs?

An ID can only be part of one family at a time. If the child has two IDs then yes, each ID can be part of different families, but note that managing two IDs has its own difficulties since devices cannot be signed into multiple IDs at a time. Switching between IDs is not easy and there can be other issues:

See and remove your devices that are associated with Apple ID purchases - View and remove your devices that are associated with Apple ID purchases - Apple Support - Read "More about associated devices" at the end where it refers to the 90 day wait. This applies to re-downloading past purchases (you can make new purchases), automatic downloads, and iCloud based services such as Family Sharing, Match, and Apple Music.

Basically there is no satisfactory workaround to the family limit. You are not the first to have posted about this situation and you are welcome to provide feedback to Apple. I suspect there is no simple solution that would meet all the requirements of the parties involved since I have seen this issue posted here many times in the many years I have been on this forum..

Product Feedback - Apple

Others have reported that and I have no idea why you would see it if both of you have your countries set to be the same. Ask Apple, and if you find out please let us know because I have seen similar posts by others.

Refer to this page for Apple Support features ➔ Contact - Official Apple Support

If the presented options do not resolve your issue, keep experimenting with any series of selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

This page has telephone numbers for contacting Apple for support and service ➔ Contact Apple for support and service - Apple Support

States, yes, she can be added. The restriction applies to countries or groups of countries such as the European Union.

Then as I wrote above, basically no.

If my daughter is on family sharing only with hubby, can I add her to mine as her mom? I’m in a different state.

She gets rejected every time I try. We are both in US and everything checks out. Any ideas?