Three panel heat stake structure

A trim panel assembly which provides support for the interior panels during a heat staking process, even when the interior panels overlap an outer panel, is provided. The trim panel assembly includes a first support boss extending from an inner surface and an outer surface which is adjacent a weld horn backing plate during the heat staking process. A second panel includes an outwardly extending elongated stud extending from an inner surface, and a support boss extending from an outer surface. An accessory panel having an aperture is aligned with the second panel such that the elongated stud passes through the aperture. During the heat staking process pressure is applied to the stud of the second panel which is supported by the weld horn backing plate through the contact between the support boss of the first panel and the boss of the second panel.