You can add extra large borders by doing them kind of Quilt As You Go style. You cut the fabric pieces needed for the front and back of one side. You lay the front fabric strip right side down on the quilt and pin the edge to the quilt edge. You lay the back fabric strip on the back in the same manner with a strip of batting and pin the edge. You then sew the pinned edge by machine and smooth all the fabric outward over the newly attached batting to have the extended side (quilt now or later)You work your way around the quilt doing each side in the same manner. When all done you can quilt the edge extensions if you haven't already done them one at a time. Put on a new binding and you are done.