Does a party have jurisdiction to bring a supplemental pleading that alleges that a party was involved in a dispute with the other party before the date of filing?

Our dissenting colleague relies on Morongo Band of Mission Indians v. California State Board of Equalization, 858 F.2d 1376 (9th Cir.1988), for the proposition that where the district court does not have subject matter jurisdiction over a matter at the time of filing, subsequent events do not confer subject matter jurisdiction on the district court. Dissent at 1068. We find this argument inapposite because, unlike the present case, Morongo did not involve a supplemental pleading, much less one with allegations of events that occurred after the commencement of the action.