You Can try this.....
DataSet ds = new DataSet();
DataTable tbl1 = new DataTable();
ds.Tables.Add(tbl1);
DataColumn col1 = new DataColumn("EmpID", Type.GetType("System.Int32"), "");
col1.AutoIncrement = true;
col1.AutoIncrementSeed = 1;
DataColumn col2 = new DataColumn("Name", Type.GetType("System.String"), "");
tbl1.Columns.Add(col1);
tbl1.Columns.Add(col2);
tbl1.PrimaryKey = new DataColumn[1] { col1 };
DataRow rw1 = tbl1.NewRow();
rw1["Name"] = "Manoj Savalia";
tbl1.Rows.Add(rw1);
DataRow rw2 = tbl1.NewRow();
rw2["Name"] = "Savalia";
tbl1.Rows.Add(rw2);
ds.AcceptChanges();
DataTable tbl2 = tbl1.Clone();
DataColumn col3 = new DataColumn("Address", Type.GetType("System.String"), "");
tbl2.Columns.Add(col3);
DataRow rw3;
rw3 = tbl2.NewRow();
rw3["EmpID"] = 10;
rw3["Name"] = "Test";
rw3["Address"] = "Ahmedabad";
tbl2.Rows.Add(rw3);
ds.Merge(tbl2, false, MissingSchemaAction.Add);