RCW 26.27.221Jurisdiction to modify determination.Except as otherwise provided in RCW 26.27.231, 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 RCW 26.27.201(1) (a) or (b) and:(1) The court of the other state determines it no longer has exclusive, continuing jurisdiction under RCW 26.27.211 or that a court of this state would be a more convenient forum under RCW 26.27.261; or(2) A court of this state or a court of the other state determines that the child, the child's parents, and any person acting as a parent do not presently reside in the other state.[ 2001 c 65 s 203.]
Washington Legal Code