Sub RunMerge()

    Dim wd As Object
    Dim wdocSource As Object
    Dim Last_Row As Integer

    Dim strWorkbookName As String

    Last_Row = Worksheets("_Main").Cells(52, 6).Value

    Const wdFormLetters = 0, wdOpenFormatAuto = 0
    Const wdSendToNewDocument = 0, wdDefaultFirstRecord = 1, wdDefaultLastRecord = -16

    On Error Resume Next
    Set wd = GetObject(, "Word.Application")
    If wd Is Nothing Then
        Set wd = CreateObject("Word.Application")
    End If
    On Error GoTo 0

    Set wdocSource = wd.Documents.Open("C:UsersevieraDesktopCertificateTemplateCertificateTemplate_Re-entryV1.docx")

    strWorkbookName = ThisWorkbook.Path & "" & ThisWorkbook.Name

    wdocSource.MailMerge.MainDocumentType = wdFormLetters

    wdocSource.MailMerge.OpenDataSource _
            Name:=strWorkbookName, _
            AddToRecentFiles:=False, _
            Revert:=False, _
            Format:=wdOpenFormatAuto, _
            Connection:="Data Source=" & strWorkbookName & ";Mode=Read", _
            SQLStatement:="SELECT * FROM `_Main$`"

    With wdocSource.MailMerge
        .Destination = wdSendToNewDocument
        .SuppressBlankLines = True
            With .DataSource
                .FirstRecord = wdDefaultFirstRecord
                .LastRecord = wdDefaultLastRecord
            End With
        .Execute Pause:=False
    End With

  wd.Visible = True
    wdocSource.Close SaveChanges:=False

    Set wdocSource = Nothing
    Set wd = Nothing

End Sub

With wdocSource.MailMerge
    .Destination = wdSendToNewDocument
    .SuppressBlankLines = True
        With .DataSource
            .FirstRecord = wdDefaultFirstRecord
            .LastRecord = wdDefaultLastRecord
        End With