I could see them going with Renee.
If it's a girl. If it's a boy, it would be René.
(I know which it is, but you'll have to wait to find that out.)
I had a feeling that was the correct spelling of his nephew's name, but decided to go with the original poster's spelling of it. For the record, I have a male cousin who's parents chose to spell his name Renee, so I don't assume anything when it comes to that spelling.