DataTable Cannot Be Cast To MyTable Unless DataTable Was First Cast From MyTable

I have a class that inherits DataTable, because we needed a couple of extra properties and methods.I did not create a derived DataSet to hold them because you can add myTable to a dataset because myTable is ultimately, a DataTable after all.My issue comes when I've used ReadXml or adapter.Fill or some other method to fill a DataSet.So when I attempt to set myTable = DataSet.Tables(0), I get the InvalidCast Exception or whatever it is.I know that DataTable cannot be cast to myTable unless the DataTable was first cast from myTable.So I feel that by some combination of nested Casts it could be done.I want to override the Copy method of the DataTable or the Widening and Narrowing operators or even all of the above. Some one please tell me it can be done.Now, I do have something that works for now, but it just feels sloppy to me and I know there HAS to be a better way.[code]