6-57 (9th Cir. 2002) (referring to the "fundamental principle" that parties who may be affected by a contract action must be joined to it); see also Rojas v Loewen Group Intl., F.R.D. 356 (D.P.R.I 1998) ("Generally, in breach of contract actions, all parties to the contract arc necessary ones"); see also Travelers ndem. C