Section 254. Presentation by corporation counsel, county attorney or district attorney

(a) The family court  or  the  appropriate  appellate
  division of the supreme court may request the corporation counsel of the
  city  of New York or the appropriate county attorney to present the case
  in support of the petition when, in the opinion of the family  court  or
  appellate division such presentation will serve the purposes of the act.
  When  so  requested,  the  corporation  counsel or county attorney shall
  present the case in support of the petition and assist in all stages  of
  the  proceedings,  including  appeals  in  connection therewith. Nothing
  herein shall be deemed to affect the provisions of section five  hundred
  thirty-five of this chapter.
    (b)  In all cases involving abuse, the corporation counsel of the city
  of New York and outside the city of New York, the  appropriate  district
  attorney shall be a necessary party to the proceeding.