Colorado limits back-to-back motions that would substantially change the child’s primary residence, generally prohibiting a new motion within two years after the prior motion was decided. An exception applies if affidavits show the child’s current situation may endanger physical health or significantly impair emotional development. Another exception exists when the primary residential parent intends to relocate in a way that substantially changes the child’s geographic ties. These exceptions allow the court to consider urgent or material changes despite the two-year limit. Routine schedule tweaks that do not change primary residence are treated differently. Review the statute text and the Judicial Branch instructions for exact language.