I have been researching my family for over 20 years. I have come to the conclusion that at some point the surname was mis-spelt and was originally derived from Edney.
I have registered the surname Edney with the Guild of One Name Studies and research the surname worldwide.
However if you are an EDNAY l'd love to hear from you because as far as l can see at the moment my own small family circle are all the Ednay's that exist. Unless of course you know something different !