Just a small correction for the post but ss of October 11, 2016 MillerCoors is now wholly owned by the Molson Coors brewing Company. ABInBev had to sell those brands as part of the anti-trust agreement.
Coke has phosphates too, I'm not sure which has more though. It does give it that dry or crisp flavor though. It's also used as a preservative of sorts to keep bacteria and mold from growing in the sugar in the soda.
If your family hasn't come to visit yet you should have them grab some Port City as well. As others have said Devil's Backbone makes some amazing beer! These are two of my favorite breweries in VA.
Since you can step up to increase the size of starters you should be fine spliting them into multiple starters and step them up as well. Have you checked mrmalty on this yet to see the size of starter you'll need?