Section 311.5. Amendment of the petition

1. At any time before or during
  the fact-finding  hearing,  the  court  may,  upon  application  of  the
  presentment  agency and with notice to the respondent and an opportunity
  to be heard, order the amendment of a petition with respect to  defects,
  errors  or  variances  from the proof relating to matters of form, time,
  place, names of persons and the like, when such amendment does not  tend
  to  prejudice  the  respondent  on  the  merits. Upon permitting such an
  amendment, the court must, upon application of the respondent, order any
  adjournment which may be necessary to accord the respondent an  adequate
  opportunity to prepare his defense.
    2. A petition may not be amended for the purpose of curing:
    (a) a failure to charge or state a crime; or
    (b) legal insufficiency of the factual allegations; or
    (c) a misjoinder of crimes.