FAA Revoking Standard Airworthiness Certificate DG-505

We imported a DG-505 Elan Orion built at the AMS Flight, d.o.o. (AMS)
factory in Slovenia in 2006. It came with a Slovenian Certificate of
Airworthiness and an AMS data plate. It was built under a German
Standard Airworthiness Certificate which designates AMS in Slovenia as
the manufacturer. DG is the owner of the European Standard Flight
Certificate.

At the time of import the U.S. Standard Type Certificate designated
the DG factory in Germany as the only acceptable manufacturer making
no mention of AMS in Slovenia. To correct this situation the Small
Aircraft Directorate at the FAA for gliders rewrote the type
certificate to make AMS in Slovenia an acceptable manufacturer. This
in part allowed the glider to receive a U.S. Standard Airworthiness
Certificate.

Also the glider did not have a German certificate of airworthiness but
only a Slovenian certificate of airworthiness. AMS had not sent the
aircraft to Germany to receive a German certificate of airworthiness.
The FAA was initially demanding a German airworthiness certificate but
again the FAA directorate modified the U.S. certificate to make any
EASA (the new European Union aviation administration) member nation as
an acceptable supplier of an airworthiness certificate. Because
Slovenia was on the cusp of being a member of EASA in 2006 (and now is
a full member) the designated airworthiness representative granted the
U.S. Standard Airworthiness Certificate.

Now 2 years later the FAA has told us its own actions were a mistake
and is about to revoke the standard airworthiness certificate if we do
not relinquish it freely. The FAA is saying that the changes to the
U.S. certificate that were made by the directorate in Kansas City were
in error. They are indicating that they did not realize that Elan
aircraft were not built in Germany and because the FAA has no
bilateral agreement (BASA) with Slovenia the certificate must be
relinquished.

Can the FAA do this at this late date? DG and AMS have not been
willing to resolve this issue and have basically said that the only
alternative is for us to ship the aircraft back to Germany and have
the aircraft reissued at our own expense.

Thanks for any help!
N505LG