A manufacturing system for laying up a stringer laminate, comprising: a lamination surface; and a plurality of lamination heads configured to dispense composite material along a dispensing direction and to dispense laminate plies on the lamination surface and on previously-formed plies during relative movement between the lamination surface and the lamination heads along a direction generally aligned with the dispensing direction, the plurality of lamination heads including: at least one frame filler outer ply lamination head configured to laminate a plurality of frame filler bottom plies at spaced intervals along the lamination surface to define a plurality of frame filler locations; at least one frame filler inner ply lamination head configured to laminate one or more frame filler inner plies over a protruding portion of the frame filler bottom ply at each frame filler location such that an overlapping portion of each frame filler bottom ply is non-covered by the frame filler inner ply at each frame filler location; and at least one stringer body lamination head (210, 212, 214) configured to laminate one or more stringer body plies defining a stringer body portion extending along the lamination surface and overlapping the overlapping portion at each frame filler location such that each stringer body ply is in side-by-side arrangement with a frame filler inner ply; and wherein: the at least one frame filler outer ply lamination head is configured to laminate a frame filler top ply over the one or more frame filler inner plies at each frame filler location such that the one or more frame filler inner plies at each frame filler location are captured between a frame filler bottom ply and a frame filler top ply, and resulting in an uncured stringer laminate having a plurality of frame filler portions protruding laterally from the stringer body portion. a lamination surface; and a plurality of lamination heads configured to dispense composite material along a dispensing direction and to dispense laminate plies on the lamination surface and on previously-formed plies during relative movement between the lamination surface and the lamination heads along a direction generally aligned with the dispensing direction, the plurality of lamination heads including: at least one frame filler outer ply lamination head configured to laminate a plurality of frame filler bottom plies at spaced intervals along the lamination surface to define a plurality of frame filler locations; at least one frame filler inner ply lamination head configured to laminate one or more frame filler inner plies over a protruding portion of the frame filler bottom ply at each frame filler location such that an overlapping portion of each frame filler bottom ply is non-covered by the frame filler inner ply at each frame filler location; and at least one stringer body lamination head (210, 212, 214) configured to laminate one or more stringer body plies defining a stringer body portion extending along the lamination surface and overlapping the overlapping portion at each frame filler location such that each stringer body ply is in side-by-side arrangement with a frame filler inner ply; and wherein: at least one frame filler outer ply lamination head configured to laminate a plurality of frame filler bottom plies at spaced intervals along the lamination surface to define a plurality of frame filler locations; at least one frame filler inner ply lamination head configured to laminate one or more frame filler inner plies over a protruding portion of the frame filler bottom ply at each frame filler location such that an overlapping portion of each frame filler bottom ply is non-covered by the frame filler inner ply at each frame filler location; and at least one stringer body lamination head (210, 212, 214) configured to laminate one or more stringer body plies defining a stringer body portion extending along the lamination surface and overlapping the overlapping portion at each frame filler location such that each stringer body ply is in side-by-side arrangement with a frame filler inner ply; and wherein: the at least one frame filler outer ply lamination head is configured to laminate a frame filler top ply over the one or more frame filler inner plies at each frame filler location such that the one or more frame filler inner plies at each frame filler location are captured between a frame filler bottom ply and a frame filler top ply, and resulting in an uncured stringer laminate having a plurality of frame filler portions protruding laterally from the stringer body portion.