Shader: Mesh with Grass and Wind

So, I have a functioning voxel engine that creates smoothed terrain in chunks of 1x1x1 meter in a 1024 radius around my player. I wanted to create a geometry shader that not only continues to texture the ground appropriately, but also creates grass (preferably waving with the wind). I have found some basic billboard geometry shaders to get me started, but they seem to cause the mesh to stop texturing. Is there anyway to do both from one shader? Do I pass the mesh triangles and the new grass triangles on to the fragment shader with a flag?

I have written some shaders before in OpenGL, but my experience is still around intermediate.

Thanks in advance!