Mont. Code Ann. § 7-3-4206

The territorial limits of such city shall remain the same as under the former organization, and all rights and property of every description which were vested in any such city under its former organization shall vest in the same under the organization herein contemplated, and no right or liability either in favor of or against it existing at the time and no suit or prosecution of any kind shall be affected by such change unless otherwise provided for in this part.