If I'm slow cooking a soup should I wait to add any dairy until the end?

I make a lot of milk/ cream soups, most which also require the addition of a couple tablespoons of vinegar to the soup. In order to add the vinegar and not have it curddle the dairy, I have to have the soup at a rolling boil for a few minutes first. Using cream and cream cheese, you might want to bring the temperature up slowly to avoid any separation of the fats/ oils.