The photo below show the top drawer blade and top drawer center divider being glued into the case. The top drawer center divider is blind sliding dovetailed into the top drawer blade, the notch in the top of the top drawer center divider receives the front case rail, the front case rail has two tendons 1/4" x 1/2" that will fit into the the front case styles (the three parts are currently sitting on the top of the case)..
The front case rail and styles being glued up and clamped, the piece of MDF is a spacer to keep everything square..
Close up of hidden screws used to secure the front rails to the drawer blades along with a well placed dab of hide glue.. The recessed area will eventually receive the corner columns, the quarter columns will hide the screws..