In a medium saucepan, bring the 6 cups of bone broth, 2 cups of water, and 2 teaspoons of soy sauce to a boil. Reduce to a simmer and add the dried porcini mushrooms. Let them soften for 5–10 minutes, then remove with a slotted spoon, finely chop, and set aside. Keep the broth on a low simmer for later use.
In a large Dutch oven or heavy pot, melt 4 tablespoons of butter over medium heat. Stir in 2 tablespoons of olive oil.
Add the chopped onions and sauté until translucent, about 8 minutes.
Mix in the cremini mushrooms, chopped porcini mushrooms, and minced garlic. Cook for about 5 minutes, until the mushrooms soften and release their juices.
Stir in the Arborio rice, ensuring each grain is coated. Toast gently for about 2 minutes.
Pour in the dry white wine and cook until mostly absorbed, stirring frequently.
Begin adding the hot broth, one cup at a time, stirring often to help the rice absorb the liquid. Repeat this process for about 30 minutes, until the rice is creamy and tender but not mushy.
After the last addition of broth, stir in the grated Parmesan and chopped parsley. Season with salt and pepper to taste.