Render with GL lines under Sprites

I googled this problem, nothing I may use so far. I want to render lines inside **OnPostRender()** with **GL.Vertex3()** etc. commands. However, all **lines render Over every sprite**. - tried to attach several different shaders to lineMaterial, still rendering over sprites - tried changing Z position depth etc. - OnPreRender() not working, yep, script is attached to camera It seems it cannot render over Material-Default, but this cannot be used for sprites. Do you have please and Idea how can I make it render under my sprites?? Don`t want to hack-spawn dozen objects with line renderers.....