Family member location not shared

Your description sounds as if your family member has chosen not to share their address. Even in a Family Sharing group a member must give permission to have their location be known in Find My and in Messages.

This is controlled in Settings > [Your Name] > Find My > Share My Location

If Share My Location is green it is active and will be shared. If it is inactive it will not be shared.

Do you have screentime on her device? You may need to make sure the Find My app is always allowed. That's what worked for me with my son.