Thanks, Kevin.

That works for saving new rows. I had already coded a kluge which also works. In Professional VB.NET, 2nd Ed. (Wrox), chapter 16, page 562 it says "You need to select another row in the DataGrid in order for the changes to be made to the DataSet,...". So I put this in my form's HookPreSave:
Me.grdCarrier.NavigateData(mmNavigate.First)
Me.grdCarrier.NavigateData(mmNavigate.Last)
This also works, although I don't know why. Why does it work?

Also why does my mmDataGrid turn into a red box with red diagonals everytime I click my mmDelete button? I have set the Binding source of the button to the child business object. There is also a separate delete button for the parent bizobj.