I would check out the fabric first, sheets can be used for backings, maybe not preferable for hand stitching, but the first quilt teacher I had said that she used sheets all the time for quilt backings. With regard to drapery fabric, check to see if it's washable, as I think the drapery fabric would be the same as using denim for quilts, only with prettier designs and colors. I have used some drapery fabric samples in baby quilts for children's hospitals from donations.