A hot runner apparatus includes a mold plate defining a pocket; a plurality of sub-manifolds; and a bridge manifold positioned in the pocket and between the sub-manifolds. The bridge manifold and the sub-manifolds are oriented in a common plane. The bridge manifold receives a melt from a melt source. Each of the sub-manifolds is coupled to the bridge manifold to receive the melt from the bridge manifold via a junction between an opening of a network of melt channels within the bridge manifold and an opening of a network of melt channels within each of the sub-manifolds. The sub-manifolds are urged against the bridge manifold to form a seal therebetween, when the bridge manifold and the sub-manifolds thermally expand urging the sub-manifolds against contact regions of a pair of opposing walls of the pocket. The respective opposing walls define a hollow region separated from the respective contact regions by a wall portion.