This will ungroup the grouped ovals. Need to be grouped after again together with the arrows I would think.
Try on a copy of your workbook as I am pretty sure that there will be follow up questions coming.
Dim shp As Object
For Each shp In ActiveSheet.Shapes
If shp.AutoShapeType = msoShapeOval Then
ActiveSheet.Shapes.AddShape(msoShapeDownArrow, shp.Left + shp.Width / 2 - 5, shp.Top, _