Did you only want to duplicate the field group? If you did, I believe you can export the field group from “Custom Fields > Tools” (PRO version) or “Custom Fields > Export” (Free version). You can also create the field group by using PHP code. Just make sure that you can load the code from your second blog.
If that’s not what you want, could you please explain it to me again?
Hmm…its almost duplicate, but this need be more easy. Let me show all situation.
I have 30 blogs. The first is that have the default configs and have a mother theme. The other 29 blogs use the child theme and have the default configs from Blog 1.
If i export the Field Group from the First Blog with PHP Code and save this on mother theme will work. The problem is that i make changes in Field Group 3 times at day. So i think that can be maked more easily.
Maybe add some filter that function then search in the field-group posts at current blog and on first blog.