In Prudential Prop. & Cas. v. Keystone Ins., 286 N.J. Super. 73, 668 A.2d 92 (Law Div.1995), the injured passenger's primary insurer brought a declaratory judgment action, seeking determination that it was an excess carrier as to liability for passenger's UIM benefits and that, Keystone Insurance, the insurer of the host vehicle involved in the accident, was the primary carrier. Id. at 74-76, 668 A.2d 92. Prudential had previously paid the UIM claim and sought reimbursement from Keystone. Keystone acknowledged that it provided primary UIM coverage to the injured passenger, but claimed that the failure to receive Longworth notice should bar any recovery under its policy. The trial court reasoned: In the normal situation, recovery of UIM benefits under Longworth depends upon notice to one's own UIM carrier that the tortfeasor has offered a settlement. In turn, if the noticed carrier takes the position that its policy is excess or "co-primary" it, not the insured, has the duty to relay that notice to the alleged primary carrier promptly, and provide that carrier reasonable time to consent or to tender the settlement amount to protect its subrogation rights. In that fashion the excess carrier takes both the responsibility and the risk attendant to the protection of its own interest. I recognize that sorting out the primary-excess issue may well require more time than the presumptive 30 day notice period set forth in Longworth. Therefore, the carrier claiming coverage as excess should also promptly alert its insured of its position and of the potential delay necessary to resolve this additional issue. An unreasonable delay, however, would allow the excess carrier either to consent or to tender a matching offer without prejudice to its rights over against the primary carrier. Failure on the part of the injured claimant's own carrier to relay notice to the alleged primary carrier would, in most cases, be fatal to its right to recover UIM benefits paid to its insured. Id. at 77-78, 668 A.2d 92.