We review a district court's denial of a motion to file a supplemental pleading for an abuse of discretion. First Security Bank of Missoula v. Ranch Recovery Ltd., 1999 MT 43, P24, 293 Mont. 363, 370, 976 P.2d 956; see also Hughes v. Pullman, 2001 MT 216, ΒΆ 40, 306 Mont. 420, 428, 36 P.3d 339, 345.