Posting another response because I think editing this into my other one would get too muddled.
The vice versa situation: I adore
Edie. I really like
Edith, too, so that wouldn't be a problem to me, but
Edie as a full name would be absolutely
Fine with a capital "F". I do not understand the hate people get on over nicknames as full names. Why saddle the child with a whole long ugly name if you're never going to call them that? If the intent is to call her
Edie the whole time, why deal with
Edith at all? Just shove
Edith out of the picture. She doesn't exist. Poof! Gone!
The fierce hate of nns-as-fns does actually surprise me. How is it in any way a big deal? I fail to understand this.
/tangent