What I stated earlier was copy and paste (no interpretation) from what was fromerly known as the FAA Inspectors handbook order 8900 and is now online as FSIMS.
the debate over whether a new FAA cert would need to be issued or not surely hinges on whether the original one specifically said 'Day VFR only' on it.
Absolutely agree with you.
I would expect that a change of operating priviliges or the addition of a rating would mean reissuance of the original beacuse of some added text in which case a new 61.75 should be issued.
Certain issues will always be skewed.
To the original poster: let us know how everything worked out and if you enjoyed your flying holiday in the USA