I don't know the specifics of the standards in question, but many manufacturers makes seats there are approved in several countries (Britax comes to mind). If I were you, I would look for a manufacturer who sells seats in both countries where the standard applies, and then email them. What you may run into is that the same seat is sold under different names, with different 'approval stickers' on - so that technically you can't use it in two different places. Maybe a manufacturer can work with you.