Turn the knee high inside out and lay flat on a cutting mat.
Using a straight edge (or just wing it with a pair of scissors) cut off the toe seam and ribbed calf portions.
Weave a needle through all 4 layers of nylon making sure to catch the underside as you go.
Scrunch the nylon in the middle and wrap your thread around several times. Secure with a few stitches in the back or tie several knots with your thread tails. Make sure you pull tight to create a secure scrunch.
This is what it looks like before you cover your seam.
Finally take a piece of 5/8" grosgrain ribbon and heat seal the end with a lighter or wood burner tool. Hot glue one end to the back of the band over the seam. I like using 5/8" ribbon since it's a better width to accommodate small and large bows.
Wrap the ribbon around to measure how much you need to cover the seam. Cut and seal the end as before. Place hot glue on the already glued ribbon portion in the back. Wrap the free ribbon piece around the front of the seam and place over the hot glued portion on the back. This completely covers the seam.
Finished! Now just clip on your bow to the front.