"Kammerherrenschl?ssel" - who can help?

[Kapitular]

This "Kammerherrenschl?ssel" was awarded in Oldenburg before 1829 under the duke Peter Friedrich Luwig. It shows his code "P". After his death followed Paul Friedrich August, later Nicolaus Friedrich Peter and finally the last one, Friedrich August. From this last one I know a "Kammerherrenschl?ssel" with his chiffre "FA".

My questions:

Had the granddukes Paul Friedrich August and Nikolaus Friedrich Peter "Kammerherrenschl?ssel" with their own chiffres, for example "PFA" or "NFP" ? Did anyone of you ever see a key with these chiffres ?

Maybe, you can help me.

Best regards

Kapitular