Good morning! Not that I am aware of. Would be also interested in a "standardized" form. But I bet, there isn't ! Take care!

The GenDec is more of a Customs document and of no interest to the NAAs. The only country in Europe I have been to that requires a GenDec for all international flights, including within the common travel area, is The Netherlands.

Axel: the GenDec is only applicable for the UK flying from the Netherlands. Not to fly to any other country with a GA non commercial flight

I didn’t see a General Declaration in decades but in the last few months, flying into Bulgaria, Turkey and Georgia, I became aware of it being (mis)used for purposes beyond the customs procedures. In said countries it is required to be filled out as both a crew and passenger manifest and is required in order to to be allowed access to the SRA and CSRA at all - even if no flight is intended! From the question I gather that this (mis)practice may also encompass Greece? In answer to the question: No I don’t now of a standardised form for GA to serve as a passenger manifest. If not in all of Europe, then surely for any flight within EU there is no (or rather should not be any) need for a Gen Dec either as free movement of persons and goods is part of the basic liberties in the EU and EEC.