I have a Disney Princesses blanket that I'm trying to convert to a picnic blanket. It's made of a Polycotton blend, and looks like a small bedspread, in fact like many picnic blankets I've seen, but it lacks a waterproof bottom. I bought some ripstop nylon for that. I am a total novice BTW, hence my question. A friend told me that when I sew the nylon to the blanket, I don't need a special foot on my machine, I just go slow and turn the fabric when I get to the rounded corners. I just wanted to confirm that. Also, the blanket has bias tape as the border, which gives it the "finished" look. My question is, should I take off the current bias tape with a seam ripper, then sew on the nylon, then put the tape back on, or sew the nylon on, the get more new bias tape and finish it off? It would be rather labor intensive I guess to take off the existing bias tap, but I'm willing to do that if it'll work/look better when it's finished. TIA!