We scrounged some time from the Wing Chun class we do Friday nights to work on a drill I'd been cooking up for the Dai parry. Begin in guard across from your partner, and have your partner Dian at the center of your chest. You should probably wear a protective mask and your partner should aim to stop short six inches from you for safety.
Begin by slapping the attack at 90 degrees to the blade from a variety of angles. Practice until you can parry without panicking, and block the blade just enough so that it would miss you only be a few inches instead of a few feet.
Once you are comfortable with this, try to match the entry speed of the attack and bring (Dai) the parry back toward you. Imagine that you are gently touching and guiding the tip of their blade into and empty and harmless space of your choosing, such as the space next to your ear above your shoulder. Practice until the motion is supple and gentle, and no longer a smashing of blades together but so gentle you could imagine yourself conducting the Dai with just a rolled up newspaper.
Finally, add a gentle step in with your Dai parry. 90 degrees away from the attack at first, and then smaller distances and more toward your opponent as you gain confidence.
If you become smooth at linking your Dai to a counterattack with smooth footwork, you will be able to move with harmony around your opponent, effortlessly evading their attack while maneuvering to attack.