Printing bulk of letters all together instead of printing one after another

Try to use this code. Do your command call Sub cmd_complete.
This macro will copy all your sheet in a new workbook called 'myLetters.xls' auto saved in your 'my document' folder.
when you close your workbook you will see workbook 'myLetters.xls' with the copy of all your letters.

See attached file, I hope it's what you need.

Regards,
Antonio

Private Declare Function SHGetSpecialFolderPath Lib "shell32.dll" _
      Alias "SHGetSpecialFolderPathA" (ByVal hwnd As Long, _
      ByVal pszPath As String, ByVal csidl As Long, _
      ByVal fCreate As Long) As Long
Private Const MAX_PATH = 260

Const myWbName As String = "myLetters.xls"

Option Explicit
Sub cmd_complete()
   Dim myDocPath As String, myFileName As String
   Dim myWb As Workbook
   
   On Error Resume Next
   Set myWb = Workbooks(myWbName)
   On Error GoTo 0
   
   Application.ScreenUpdating = False
   Application.EnableEvents = False
   If myWb Is Nothing Then
      'wb not opened
      myDocPath = GetSpecialFolderPath("5") & "\"
      myFileName = myDocPath & myWbName
      If Dir(myFileName) <> "" Then
         'wb exists, then open it
         Set myWb = Workbooks.Open(myFileName)
      Else
         'wb doesn't exist, it will be created and saved
         Set myWb = Workbooks.Add
         'delete all sheets
         Application.DisplayAlerts = False
         Do While myWb.Sheets.Count > 1
            myWb.Sheets(2).Delete
         Loop
         Application.DisplayAlerts = True
         myWb.Sheets(1).Name = "noprint"
         myWb.SaveAs Filename:=myFileName, FileFormat:=xlNormal, _
               Password:="", WriteResPassword:="", _
               ReadOnlyRecommended:=False, CreateBackup:=False
      End If
   End If
   
   'copy sheet to myLetters.xls
   ThisWorkbook.ActiveSheet.Copy after:=myWb.Sheets(myWb.Sheets.Count)
   ThisWorkbook.Activate
   myWb.Save
   
   Application.EnableEvents = True
   Application.ScreenUpdating = True
End Sub
Private Function GetSpecialFolderPath(ByVal fldNo As Long) As String
   Dim Path As String, hwnd
   Path = Space$(MAX_PATH)
   If SHGetSpecialFolderPath(hwnd, Path, fldNo, False) Then
      GetSpecialFolderPath = Left$(Path, InStr(Path, Chr(0)) - 1)
   Else
      GetSpecialFolderPath = ""
   End If
End Function