"We review de novo the district court's determination that the pleading, motion or other paper violates Rule 11. We review the district court's findings of fact underlying that conclusion to determine whether such findings are clearly erroneous. If the court determines that Rule 11 was violated, then we review the district court's choice of sanction for abuse of discretion." Byrum v. Anderson, 2007 MT 107, ¶ 19, 337 Mont. 167, 159 P.3d 1062. "'A district court retains the necessary flexibility to deal appropriately with violations of Rule 11 and has discretion to tailor sanctions to the particular facts of the case.'" In re Guardianship and Conservatorship of A.M.M., 2015 MT 250, ¶ 73, 380 Mont. 452, 356 P.3d 474 (quoting Davenport v. Odlin, 2014 MT 109, ¶ 9, 374 Mont. 503, 327 P.3d 478).