The TMSTableData Component Assign function only copy the source table fields, but not copy the source data! I strongly recommend that can copy the all data like the TMSTable component.
for example:
self.MSTable1.First;
self.MSTableData1.Close;
self.MSTableData1.FieldDefs.Clear();
self.MSTableData1.Assign(self.MSTable1);
self.MSTableData1.Active:= true;

The MSTableData1 not copy the MSTable1 data , but it copy the fields