Use Texture to break transition between automatically-blended Landscape Layers

Hi all, in the Stylized Rendering content example project, the landscape’s material, M_Terrain_Ground_A, uses an automatic blending method between grass and rock based on surface normal (1st image below). This uses a weight-blended landscape layer. However, for the “Beach Color and Mask” portion of the material, the layer is painted on manually, however, it uses a unique speckled transition between the beach texture and other layers. I am wondering if it is possible to get this same type of textured blending on the automatic transition between the grass and rock layer, rather than the solid transition line currently used in the material.

Thanks for any insights you can provide on this!