Substitution of parties alters when a suit is treated as instituted, subject to good faith mistake exceptions. When a new plaintiff or defendant is added or substituted after a suit begins, the suit is deemed to have been instituted as to that party on the date they were made a party, but the court may direct an earlier deemed institution date if the omission arose from a mistake made in good faith. This deeming rule excludes additions or substitutions resulting from assignment or devolution during the suit and excludes cases where a plaintiff becomes a defendant or vice versa.