i would suggest that your don looks into why a nurse manager is so focused on the care being given by a colleague's unit. there may be more than meets the eye here, and your "case" could just be a symptom of greater political machinations that you haven't been privy to. you've become the bullet in a battle between two factions, so it may be wise to do like one of the other respondents stated, ask for another assignment.
that said, follow your hospital's policy and procedure manual to the letter. if they want to amend it hospital wide, let them do it in writing in the p&pm first. otherwise, stick to the manual. if anyone tells you different, advised them that you're not allowed to violate institutional policy for anyone (special emphasis on the anyone, including dons, rn mgrs, mds, pts, visitors, etc.) as you work for the institution, and ultimately have to answer to them. that is, even the director of nursing, cannot violate institutional policy and procedures. she may endeavor to change it, but she, like all employees, remain bound by it.