Try below code, and hope this is what u want.

On Form1, u have more than two, but let's say there's 2 buttons
Code:
Option Explicit
Private pvarButton As CommandButton

Property Get GetButton() As CommandButton
Set GetButton = pvarButton
End Property

Private Sub Command2_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = 2 Then
   Set pvarButton = Command2
   Form2.Show vbModal
End If
End Sub

Private Sub Command1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = 2 Then
   Set pvarButton = Command1
   Form2.Show vbModal
End If
End Sub
On Form2, u need 3 textboxes for Caption, Tag, and toolTipText, and one Apply button. However, u can't edit name of button.

Code:
Option Explicit
Private pvarButton As CommandButton

Private Sub Command1_Click()
   pvarButton.Caption = txtName
   pvarButton.Tag = txtTag
   pvarButton.ToolTipText = txtToolTip

   Set pvarButton = Nothing
   Unload Me
End Sub

Private Sub Form_Load()

Set pvarButton = Form1.GetButton

End Sub
Joon