How about once the beans are cooked, You drain the liquid. That is what we do.. Or we re-fry them the next day, after they have been stored in the fridge.
To cook the beans, We add salt, salt pork, 2 chopped cloves of fresh garlic, a whole white onion, and a whole jalapeno (do not let the jalapeno break) to the beans and the water. Bring to boil, and then simmer till cooked. Add boiling water if the water gets lower than the beans. Never add cold water, it will split the beans,
Once beans are cooked (you can remove the onion and jalapeno), place oil in skillet, use slotted spoon, to spoon in beans into skillet. Mash beans with potato masher.
I have NEVER heard of adding milk to beans for any reason.. If the beans are cooked properly and not much water in the skillet for re-frying , they will not need anything to make them creamy.. Our secret is to place them in the fridge over night.