@joefromchicago,
Thank you very much for your reply.
I would like to follow up your suggestion. But in the 18the century the Flemish territory was consequently governed by the Spanish Habsburgers (till 1713), then the Austrian Habsburgers and in the end by the French (1794?). How these foreign occupators communicated with the Flemish, I don't know. Around 1765 probably in French, since French was very much spoken in the royal courts.
I could adopt the French etiquette but in a way it isn't fair. I would like to know more about the English etiquette adapted to the unique situation in 1765 in a complete wilderness but not isolated from the smell of independance that hung in the air. That period is part of the 'Enlightment'. A lot of things changed, the people to deal with, were far from their homecountries, mixed, ... I suspect it is not the same situation as in Europe.
I have even gone as far as to let the convicts and common soldiers speak a mix of Flemisch dialects... to mark the difference in social class which was, I think, very distinctive in the 18th century and even in the 19th century.
But I will keep your suggestion in mind, thank you!