The Department could not unilaterally dismiss a supplemental petition it had previously filed to remove the minor from her mother’s custody over the objection of minor’s counsel. Where minor’s counsel objects, the Department must show that dismissal is in the best interest of the child. Therefore, the trial court should have required the Department to show cause why the supplemental petition, filed here because mother failed to pick the minor up at school and was found at home incoherent, should not have been dismissed. However, here the procedural error was harmless. Further, there was insufficient evidence to support the removal of the minor from mother. A single instance of parental tardiness is not an uncommon occurrence, and there was no evidence to support an assumption that mother’s incoherence was due to drugs or alcohol.