le 15 or Rule 21 applies to the addition of a party under the Federal Rules of Civil Procedure, the Fifth Circuit resolved this issue in McLellan,. Mississippi Power & Light Co., 526 F.2d 870 (56' Cir.), vacated in part on other grounds 545 F.2d 919 (5th Cir. 1977). Plaintiff McLellan filed suit against his former employer,