I am replacing three 30 year old wood windows. Windows I am replacing are wood with integrated brick mold. Exterior siding is hardie. The entire window is coming out including the frame. I have new Pella Lifestyle windows ready to go in. New composite brick mold will go around the sides and top - should look exactly like existing. My question is what to do at the bottom. The new windows have a built-in aluminum sill. Not sure how to trim out the sill at the bottom exterior. First pic is closeup of existing window, second is the new window, and third is full view of existing.