Under Rule 19(a), a court asks first whether complete relief can be accorded to the parties to the action in the absence of the unjoined party. Fed. R. Civ. P. 19(a)(1). A Rule 19(a)(1) inquiry is limited to whether the district court can grant complete relief to the persons already parties to the action. The effect a decision may have on the absent party is not material. Field, 626 F.2d at 301 (quoting 3A James W. Moore et al., Moore's Federal Practice P 19.07-1[2], at 19-128 (2d ed. 1979)). In applying Rule 19(a)(1) the specific question is whether a court can grant complete relief to the parties before it when only one of two co-obligors has been joined as a defendant. The answer to this specific question depends on the law of contracts concerning the joint and several liability of persons who are co-promisors or co-obligors on one agreement. Two general authorities on the subject have identified a strong trend in favor of a principle that co-signers or co-obligors on a contract are jointly and severally liable for its performance. See 2 Samuel Williston, Williston on Contracts §§ 320, 336, at 649-657, 697-706 (3d ed. 1959) (while at early ...