Yes, but Gourgaud's “Nouvelle revue retrospective” (1896) Dumoulin and Cambacérès were captured on 16th carrying orders to Ney. Yet Dumoulin claims 18th, and Gourgaud's sign's off on that in 1831 when Dumoulin is seeking the rank granted by Napoleon after Waterloo. Napoleon believed orders to Grouchy may have ridden to Prussians, while Zach/Letourner talk of at least one's capture.
Same 2 officers, or 2 officers to Ney and 2 other officers to Grouchy? There were allied messengers wounded going between Quatre Bras/Ligny, so both is certainly possible.
Trying to put together the list of officers under Gourgaud in 1815 - we don't even know how many. Napoleon states that the orders to Grouchy went through Soult, and Stoffel seems to back that up. But what if one went through Gourgaud - especially if Soult's staff was busy with the OB issued the night of the 17th early morning of the 18th. Any little clue helps narrow the next search. Then, if it was a matter of capture/injury, could be records. Dumoulin was captured/injured, but where/how/by whom? Did Dumoulin tell the truth in 1852?
Whether to Ney or Grouchy it is interesting, if correct. If to Ney on the 16th, it is more evidence of Napoleon's belief that Ney had operational control over the left wing and that Napoleon is ignorant of I Corps' position. I'm definitely leaning towards de Wit's analysis that Napoleon did not send direct orders to d'Erlon/I Corps. If to Grouchy, then it could confirm what has long been dismissed.
When it comes to Waterloo, archives are incomplete and inconsistent - with many officers having nothing for the campaign yet with eyewitness testimony that confirms presence.
Bories was not at Waterloo either, yet that became part of the popular legend.
Would the Prussian/German archives have identities of French officers captured during the campaign?