How about using my solution to lace curtains that were not wide enough? I took some upholstery fabric that I washed first, and made outer side panels to hang on either side. It gives you a faux-look of lace under drapes. I like
the look so much that when I purchased sheers for my bedroom, I bought six panels of eggshell color for the center and a dark blue for each end. The whole thing hangs from just one rod. (If you carefully unstitch the edge if the white color you already have, you can connect them pretty easy. I decided not to attach mine.)