not sure how I am going to alter some sheets that I got for my mom and dad. They have a waterbed. I know that you need to have the top and bottom sewn together. but im not sure how I am going to attach the corner sections to keep the sheets on the bed. thinking since sheets are now made for deep beds that the elastic might actually keep the sheets on the bed since they are deep ones. those of you that have waterbeds, how would you alter them? i have looked it up on pintrist and on google but cant seem to find a good tutorial. Any suggestions?