My employer is constantly using the word "behalves" in his letters and documents when referring to more than one person. However, I have explained to him that it is grammatically incorrect and should use the phrase "this letter is being sent on your behalf."
How should the word behalf in plural form be used in documents and/or letters?
It is an almost obsolete, but correct, plural. I would not try to change my boss's grammar - could lead to trouble