Mont. Code Ann. § 41-6-103

The compact administrator is hereby authorized and empowered to enter into supplementary agreements with appropriate officials of other states pursuant to the compact. In the event that such supplementary agreement shall require or contemplate the use of any institution or facility of this state or require or contemplate the provision of any service by this state, said supplementary agreement shall have no force or effect until approved by the head of the department or agency under whose jurisdiction said institution or facility is operated or whose department or agency will be charged with the rendering of such service.