I gave my sister 6 memory quilts for Christmas pieced together from my nephew's clothes. (her son was killed in a horrible accident.) I am far from an expert, but I mixed all of the fabrics together on most of the quilts.... jeans, sweatshirts and shirts. I put fusible interfacing on the tshirts and sweatshirts. I used a #16 needed when I sewed the denim and I think I used a #12 on the other fabrics. When I quilted I used #16 as well.. I had no problems with damaged fabrics. I did use some filler fabric of horses, and wildlife that my nephew liked to help fill out the quilts. Good luck I am sure the quilts will be loved.