The Newport kit came with window inserts with white lines printed on the acrylic.  Right away I planned to replace the window inserts with clear unlined plastic since I didn't like the look of the white lines.  Initially, I looked into getting working windows, and I loved the look of the Yorktown style by Houseworks.  There were two problems with replacing the existing windows with the Yorktown working windows.  First, the working windows fit an opening 1/2" deep.  The walls are 3/8" thick.  The gap would have to be addressed either on the inside or out.  Second, and more importantly, there was the cost of replacing 16 windows (including the 2-story addition).  Since I don't plan to sit around opening and closing the windows anyway and it is more about the overall look for me, I decided to go with a more economical solution.

I purchased Yorktown window pediments to use with the existing windows.  I then cut a piece of 1/8" x 1/4" scrap wood to fit the inner width of the window.  With the existing acrylic window inserted, I lined up the new mullion piece with the middle horizontal line on the acrylic.  I will also cut a mullion piece for the interior side of the acrylic.

click image to enlarge

Upgrading with the Yorktown window pediments was no problem for the main house windows, but the dormers are constructed with the pediment as part of the overall structure - not just placed on the exterior surface as decoration.  The Yorktown pediment is taller than the one that came in the kit, and this difference created a large gap between the top of the dormer walls and the dormer roof; it also pushed the peak of the dormer too close to the top edge of the mansard roof.  To fix this, I carefully disassembled the dormer windows and cut off the amount equal to the height difference between the pediments.  I then glued the window back together.  Since I planned to replace the acrylic anyway, it didn't matter that the provided insert no longer fit properly.