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.
Any ideas?