Multiple TEXTURE Displacements (mapping) in one scene This might be a bit too special but I thought I'd just give it a try on this forum:

I have a meadow scene. And I want to have a trail running through it. I did use a displacement modifier on the small hills in the scene, and on the trail itself. 

I did paint in the texture of the trail, because it should be a different one than the texture "under" the grass (as seen in the pic). 



Now I want both textures ("brown soil under the grass" AND the "trail texture") to have a normal, displacement, occlusion, specularity and a diffuse map. But...


I only have ONE displacement connector in the material output node where I would have to put in the normal map(s)...





When I use a displacement modifier I can't place it in reference to the coordinates I already set up for the general seamless texture - so the "bumping" applies to the whole mesh and is way to big. 




How can I apply multiple textures AND THEIR MAPS to certain areas on a single plane with the same texture coordinates as in their nodes??
(I'm not totally clear on you question but I'll give it a shot.)

You can combine several displacement textures one using Mix RGB nodes.

Let's say you have a situation like this where I'm combining two textures used as displacement:



Now I want to add some voronoi noise to the whole thing, so I would just combine the bump map with a mix RGB node like this:



But as noted in one of the comments using true displacement on the material nodes is still at experimental stages and might yield unpredictable results. It might be better to combine multiple displacement modifiers, and maybe use an empty to control the coordinates for the deformation.