or
Dim GuestCB As DataGridViewComboBoxCell
GuestCB = DataGridView1.Rows(DataGridView1.RowCount - 1).Cells("Guests")
For Each RV2 As DataRowView In DV2
Dim Row2 As DataRow = RV2.Row
GuestCB.Items.Add(DVGuests.Table.Rows(DVGuests.Find(Row2(2)))("LookupName"))
Next