Except as otherwise provided in section 20-204, a court of this state may not modify a child custody determination made by a court of another state unless a court of this state has jurisdiction to make an initial determination under subdivision (1) or (2), subsection (a), section 20-201 and:
(1) The court of the other state determines it no longer has exclusive, continuing jurisdiction under section 20-202 or that a court of this state would be a more convenient forum under section 20-207; or