สงสัยเกี่ยวกับการใช้ BackgroundWorker หลายๆตัว vb.net

Imports System
Imports System.Threading

Public Class Form1

    Dim Str_Query As String
    Dim Int_TotalRows As Integer

    Private Sub ThreadStart()
        Dim strReturn As String
        Dim display As New Action(Of String)(AddressOf AddTextByDispatcher)

        '*** Process in Thread
        '*** Process in Thread
        strReturn = "String Return"
        
        Dispatcher.BeginInvoke(New AddTextDelegate(AddressOf AddTextByDispatcher), strReturn)
        '*** Process in Thread
        '*** Process in Thread
    End Sub
    Private Delegate Sub AddTextDelegate(ByVal text As String)
    Private Sub AddTextByDispatcher(ByVal strReturn As String)
        Me.txtResult.Text = strReturn
    End Sub

    Private Sub BtnProcess_Mem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnProcess_Mem.Click
        
        Dim thread As New Thread(AddressOf ThreadStart)
        thread.Start()

    End Sub