In a large mixing bowl, using your hands, mix together the beef, veal, pork, and eggs. Gently mix, don’t over do it! Now add the bread crumbs, parsley, basil, salt, garlic, and pepper and mixt it well.
Tear the bread into pieces and put in a bowl. Add the milk and let it sit for about 8 minutes, press the bread with your fingers, make sure the milk is absorbed by the bread.
Add the soaked bread to the meat mixture and mix it in. Next add the grated cheese, and 1 tablespoon of the milk (discard the remaining milk).
Cover the bowl with plastic wrap and place in the fridge about an hour.
Using an ice cream scoop, pull out chunks of meat and roll them between your hands that have been dampened with water. Place the balls on a baking sheet lined with parchment or wax paper. Refrigerate the rolled balls for at least 10 minutes.
Heat about a teaspoon of olive in a good non-stick skillet. When the pan is hot, working in batches, add the meatballs and cook them for about 10 minutes, turning them until they are browned on all sides. Transfer to a platter and set aside. (They can still be pink in the center - they will finish cooking all the way through in the marina. )
Meanwhile, in a large pot, heat the marina over medium-high heat.
Slowly, and carefully, add the meatballs and any accumulated juice to the marina. Lower the heat to medium and cook them for at least 45 minutes. Give them plenty of time to let the sauce and meatballs to get very familiar.