Hi Ed,
few remarks if useful;
domestic sales are not necessarily duty unpaid as you
create release to free import declaration and pay
duties.
if you export, you have transit.
If you move between two EU plants and
they belong to the same license - customs id, I
believe you should be able to create a t1..
if the second plant is not under the same license, then
it is domestic sales.
i Am not sure how the system would manage it
if the two EU plants belong to different licenses - customs Id.
IS it your scenario?
let us know
hope it helps
assen