It seems like this isn’t possible because ACF enforces children on the group field to have a field name that concatenates with its parent so group parent with child child will force the child to actually be parent_child. But if there were option to override this default behavior and name the child whatever you want, then it wouldn’t be a problem (You could name the child a field name that already exists and delete that field which is outside of the group).
I’m running into this right now and really wish I could group a handful of fields that already exist, but I’ve hit a wall. Any chance I can suggest the ability to override the default behavior, as described above?
