How to increase slab thickness of an already terminated surface

Dear All,

I am curious to know if pymatgen can do this; given an already created slab that is terminated symmetrically both top and bottom surface, with thickness 2nm, Is it possible to reconstruct this slab by increasing only its thickness to 8nm, such that the only layers added are between the 1nm of the top surface and the bottom of the surface with pymatgen?. See the figure below.