Option Explicit
Private Sub Form_Load()
Dim i As Integer
Dim Record As ReportRecord
Dim Item As ReportRecordItem
    
    With Me.ReportControl1
        
        For i = 0 To 2
            With .Columns.Add(i, "Column" & i, 100, False)
                .Editable = True
            End With
        Next
        For i = 1 To 5
            Set Record = .Records.Add
                Set Item = Record.AddItem("")
                    Item.CreateEditOptions
                    Item.EditOptions.AddComboButton True
                    Item.EditOptions.MaxLength = 10
                Record.AddItem ""
                Record.AddItem ""
        Next i
    
        .Populate
        .AllowEdit = True
        .FocusSubItems = True
        .SelectionEnable = True
        .EditOnClick = True
    End With
End Sub
Private Sub ReportControl1_GotFocus()
    ReportControl1.FocusSubItems = True
End Sub
Private Sub ReportControl1_PreviewKeyDown(KeyCode As Integer, ByVal Shift As Integer, Cancel As Boolean)
Dim intfc As Integer, intfr As Integer  ' focused col / row
Dim rpt As ReportControl
    
    If KeyCode = Asc(vbTab) Then
        Set rpt = ReportControl1
        intfc = -1: intfr = -1
        '
        On Error Resume Next
        intfc = rpt.FocusedColumn.Index
        intfr = rpt.FocusedRow.Index
        On Error GoTo 0
        '
        If intfc > -1 Or intfr > -1 Then
            If Shift > 0 Then
                If intfc <= 0 Then
                    If intfr = 0 Then
                        rpt.FocusSubItems = False
                    End If
                End If
            Else
                If intfc = rpt.Columns.Count - 1 Then
                    If intfr = rpt.Rows.Count - 1 Then
                        rpt.FocusSubItems = False
                    End If
                End If
            End If
        End If
    End If
End Sub

.FocusSubItems = True

.TrapTabKey = True