Furthermore 14 CFR 61, § 61.75(b)(4) ['...applicant for piggyback private pilot certificate...'] "Holds a current medical certificate issued under part 67 of this chapter or a current medical certificate issued by the country that issued the person's foreign pilot license."
Oh man. I hold a UK CAA-issued JAR-FCL conforming PPL but a Dutch-issued JAR-FCL conforming medical. With that combination I can fly an aircraft registered in any JAA state, but now you're saying it's not good enough, in this combination, to get an FAA piggyback license?