Top Law Schools

Original claim is diversity jurisdiction-If A sues B and then B makes a compulsory counterclaim back against A and also joins C in the counterclaim (pursuant to 13h/19), but C would destroy diversity, would the claim against C have supplemental jurisdiction or would B be considered a plaintiff in this scenario in which supplemental jurisdiction is not available for "claims by plaintiffs against persons made parties under rules 14,19,20,24"?

Or since B was the original defendant, supplemental jurisdiction is allowed?

Thanks for any replies!

.