If MsgBox("Delete all subform records, ...are you sure?", vbQuestion + vbYesNo) = vbYes Then
        DoCmd.RunCommand acCmdSaveRecord
        CurrentDb.Execute "DELETE * FROM YourChildTable WHERE CustID = " & Forms!YourParentForm!txtCustID, dbFailOnError
        Forms!YourParentForm![YourChildForm].Requery
    Else
        Exit Sub
    End If

Select all