In a large pot, combine chicken, onions, garlic, celery, and carrots. Cover with 12 cups water and season with salt.
Bring to a strong simmer over high heat, then reduce heat to medium-low to simmer.
Gently simmer, uncovered, for 1½ to 2 hours. Using tongs, remove chicken breasts, thighs, and legs from the pot (let any skin and bones fall into the pot), leaving everything else behind.
Pick the meat from the chicken and set meat aside to either put back into your soup, or to use in another dish.
Strain broth (you should have about 10 cups) and return to the pot. Season with Member's Mark™ Black Pepper and Mediterranean Sea Salt Grinders. Keep warm, if using same day, or let cool and refrigerate overnight.
While the soup is simmering, prepare the matzo balls: Combine matzo meal, Member's Mark™ Chopped Chives, and 1¾ teaspoons kosher salt in a medium bowl. Using a fork, incorporate eggs until well blended. Add chicken fat, followed by club soda, mixing until no lumps remain. Cover with plastic wrap and refrigerate at least 2 hours (and up to 24 hours).
Bring a large pot of well-salted water to a boil. Roll matzo ball mixture into balls slightly smaller than the size of a ping pong ball and place on a plate or parchment lined baking sheet until all of the mixture is rolled (there will be about 24 balls total).
Add matzo balls to the boiling water and cook until floating, puffed and cooked through, 10 to 12 minutes. Make sure the balls' texture is uniform in color and texture, and that they aren't undercooked in the center. Using a slotted spoon, transfer the matzo balls to the chicken broth.
Add celery (and some of the picked chicken meat, if you desire) and season again with salt before ladling into bowls, topping with Spice Islands® Dill Weed, celery leaves, and Member's Mark™ Black Pepper.