I need to make a 3D mesh over a comlex geometry. Before that I tried to make a test on spheres.

I draw a sphere with 100mm radius on the origin and a 300mm radius sphere on the origin. Thus the larger sphere takes the smaller sphere in. Then I switched to the advanced simulation mode and tried the mesh this object with 3D tetrahedrals.

What I exactly want is having a sphere inside a sphere which are meshed seperately and having node connectivity. Thus the triangles on the surface of the smaller sphere and inside surface of the larger sphere should be same. In short, I need continuity between the tetrahedrals but I dont have.

Is there any way to make 3D meshing continuous for overlapping and/or enclosing objects ?