Crumble the blue cheese and set aside.
Add the mayonnaise, yogurt, and 4 ounces (1/2 cup) of the blue cheese to a bowl. Mash the blue cheese into the yogurt and mayonnaise using a fork or a small masher.
Add the vinegar, lemon, Worcestershire, hot sauce, garlic, pepper, sugar, and parsley to the bowl.
Mix well and add an additional 2 ounces of blue cheese crumbles.
Cover the dressing and let it hang out in the fridge for at least 3 hours.