Except as provided in subsection (b) of this section, by proceeding under this subtitle, a petitioner, including a petitioner who acts on behalf of a child or vulnerable adult, is not limited to or precluded from pursuing any other legal remedy. A person eligible for relief, as defined in § 4-501 of this subtitle, is not eligible for peace order relief under Title 3, Subtitle 8A or Subtitle 15 of the Courts Article.