Ideally, both parents ought to agree on a name. So if you're not okay with either Boyd or Ethan, I think a different solution would be best.
Maybe, since Boyd comes from his side of the family, you could choose a new middle name from your side of the family. Something you like more than Ethan.
Or, maybe you could add a second middle name that you prefer to both Boyd and Ethan.
Or, maybe you could bump Boyd down to middle and choose an entirely different first name. (Because sometimes calling a person by their middle name can be confusing.)
I like both of those girl names, but I prefer Samantha because it's the standard spelling.