Partial Class Default2
Inherits System.Web.UI.Page
Dim a As String = ""
Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Button2_Click(sender, e)
Button3_Click(sender, e)
a += "我最後按了Button1"
Me.Label1.Text = a
End Sub

Protected Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
a += "我按了button2"
End Sub

Protected Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
a += "我按了button3"
End Sub
End Class

把原本每個按鈕要執行的抽出來，寫在另外的Sub
然後在按鈕按下後，依您想要的順序去執行Sub

就醬子的概念即可

以下範例：
aspx
<asp:Button ID="btn1" runat="server" Text="按鈕1" /> <br /> <asp:Button ID="btn2" runat="server" Text="按鈕2" /> <br /> <asp:Button ID="btn3" runat="server" Text="按鈕3" /> <hr /> <asp:Label ID="lblMsg" runat="server" Text="Label"></asp:Label>

aspx.vb
Partial Class Default2 Inherits System.Web.UI.Page Dim Rlt As String = "" Private Sub btn1Run() Rlt &= "執行btn1<br>" End Sub Private Sub btn2Run() Rlt &= "執行btn2<br>" End Sub Private Sub btn3Run() Rlt &= "執行btn3<br>" End Sub Protected Sub btn1_Click(sender As Object, e As EventArgs) Handles btn1.Click Rlt &= "按了btn1<br>" btn2Run() btn3Run() btn1Run() Rlt &= "<hr>" lblMsg.Text = Rlt End Sub Protected Sub btn2_Click(sender As Object, e As EventArgs) Handles btn2.Click Rlt &= "按了btn2<br>" btn1Run() btn3Run() btn2Run() Rlt &= "<hr>" lblMsg.Text = Rlt End Sub Protected Sub btn3_Click(sender As Object, e As EventArgs) Handles btn3.Click Rlt &= "按了btn3<br>" btn1Run() btn2Run() btn3Run() Rlt &= "<hr>" lblMsg.Text = Rlt End Sub End Class

就醬子
^.^a