DataSetFactory-Instance-usage

Is there a DataSetFactory.Instance method that will append to an existing dataset? The code below employing the List<string> .AddRange method works, but I'm wondering if there's a more efficient way?

CODE:
   List<string> stockList = GetUpdatedSymbols();
   dataset.Symbols.AddRange(stockList);
   DataSetFactory.Instance.AddDataSet(dataset);

In addition, is there a DataSetFactory.Instance method that will repaint/update the lower list in the screenshot below so it agrees with the upper list? Shouldn't the WPF control of the top list, whenever it changes, automatically trigger an update of the bottom list so both lists always stay in sync?

No one expects documentation for every WL utility function, but including docs for the salient ones would be nice.