I went back and found the problem. I also made the columnCount(), setData(), and data() virtual along with others requiring polymorphic behaviour. Eventually I will eliminate duplicate data in my application but for now I am using a QVector<QVariant> as my model data staging area. I found the problem to be what I mention above not being virtual along with an oversight on what order objects are constructed. I needed to properly size the QVector<QVariant> in the base class before attempting to use the index operator for QVector to insert columns at specified locations in the base class. I still welcome feedback from more experienced coders...

Thanks.