Just like at the beginning of Step 2, your three strands will become shorter. Continue to braid your three free ends until they are the same length as Rope D's free ends.

Place Rope D underneath of your braided whip so that Rope D's free ends are now running parallel to the two outermost free ends, as shown. Just like in Step 2, you will treat each set of parallel strands as a single "free end." Continue braiding as you did before.