Plot 3D scene in libGDX

This is my first day of testing libGDX after working with JOGL for almost 6 months.

Problem: I need a solution to dynamically link 3D models to other models at runtime. I am developing a simple 3D dog fighting game, and the weapons in difficult points need to be changed while playing.

What I tried: Coming from a JOGL background, I thought using the Matrix stack to implement my own scene graph - libGDX does not have a 3D scene graph. However, since libGDX has devalued OpenGL 1.0, I cannot find the push / pop matrix. Also, I know that I can apply a transformation to an object via instance.transform, but I can't think of a way to implement a scene graph with it.

Is there a built in libGDX for this?