Any reasoning for doing a hybrid make of a direct vat, with added starter? Without modifying the make parameters? Seems like you can do one or other other. If you wanted to preacidify the milk, at most, I would get it to the drain level (6.0 ish) and let the starter finish, and preferably use acid to reach target rennet pitch pH, to shorter the wait time for ripening. Direct vat acidification and normal make are completely different approaches, hybridizing them is a little tricky. If you preacidify the milk with the same amount of acid, getting it down to 5.6-5.8, it doesn't need more acid later.