Click on the "FAA Letter" at the bottom of the link below. I had to include it for mine as I had a bill of sale from who I bought it from, but not from the original owner, or the sale to the second owner... Same scenario as you. I had no problems with registration what so ever.
Edit: With this letter and explanation you are kind of skipping over the second owner transaction as the intent of the FAA tracking ownership is more about the original producer of the kit than all the people who owned it.
http://www.kitfoxaircraft.com/index.php/bill-of-sale