Agreed with the other answer. Assuming that no actual laws/regulations/rules are being violated, which is probable, the only likely solution is to complain to HR that your supervisor/manager is behaving in an unprofessional manner. It would be perfectly legal and professional to just say contact the case worker (reference the name) and copy the case worker. It is implying the case worker wrote the letter and not bothering to copy the case worker of the letter that is unprofessional. The manager can write any letter they want and tell the unhappy recipient to go complain to the case worker about it. But the entire method as it is handled is unprofessional and poorly done. Not something I would want to defend to senior management anywhere I have worked. Ordering your subordinate workers is one thing. Blind siding them by not copying them on letters you sent out in their name is something very different. My prior senior management would not have cared (much) about me getting my subordinate employees unhappy but taking an action in those subordinate's name without telling them makes me (and my bosses) look incompetent. Which my bosses would care a lot about.