Dim strsql As String, str2
strsql = "SELECT DISTINCT tblAgent.ID, tblAgent.Naim,IIf([idinvoice]=" & k0dInvoise & ",""V"",""-"") AS Инвойс " & _
"FROM tblZakaz INNER JOIN (tblAgent INNER JOIN tblPostOrders ON tblAgent.ID = tblPostOrders.ida) ON tblZakaz.ID = tblPostOrders.idz " & _
"WHERE (((tblZakaz.ID)=" & k0dInvoise & "));" ' это просто пример подставите свой запрос
str2 = "0;Поставщик; Инвойс;"
strsql = str2 & ReSource( strsql) ' функция описана ниже
With Me.List57
   .RowSourceType = "Value List"
   .RowSource = strsql
   .BoundColumn = 1
   .ColumnCount = 3
   .ColumnWidths = "0; " & .Width-twp(1) "; " & twp(2) ' twp - внутренняя процедура переводящая твипы в см
  .ColumnHeads = True
.Selected(0) = True ' выбираем первую строку в списке
.Value = .ItemData(0)
 End With

Public Function ReSource( str1 As String ) As String
      Dim strsql As String, rst As ADODB.Recordset, str2 As String, str3 As String
10    On Error GoTo ReSource_ERROR
20   strsql = str1
30    str2 = vbNullString
40       Set rst = New ADODB.Recordset
50       With rst
60       Set .ActiveConnection = CurrentProject.Connection
70      .CursorLocation = adUseServer
80       .LockType = adLockReadOnly
90       .CursorType = adOpenKeyset
100     .Source = strsql
110      .Open
120         If Not .EOF Then
130            str3 = .GetString(, , ";", ";", vbNullString)
140            str2 = Left(str3, Len(str3) - 1)
150         End If
160      .Close
170   End With
180   Set rst = Nothing
      'Debug.Print str2

Exithere:
190   ReSource = str2

200   Exit Function
ReSource_ERROR:
      'Debug.Print err.Number
210   If err.Number = -2147217904 Then Resume Exithere
220   If RejDevel00pers Then Debug.Print err.Number; Tab; err.Description: Stop: Resume
230   LibP_errorLog "MISTAKE IN  Module1", "ReSource", err.Number, err.Description & Gl0balDelimiter & Erl
240   Resume Exithere
End Function

Private Sub List57_DblClick(Cancel As Integer)
Dim str2, strsql ' (в голове поставлено DefStr S-T)
If Me.List57.Column(4) = "V" Then str2 = 0 Else str2 = k0dInvoise
CurrentDb.Execute "UPDATE tblZayClient SET tblZayClient.idinvoice = " & str2 & " WHERE (((tblZayClient.ID)=" & List34.Value & "));"
strsql = "SELECT DISTINCT tblAgent.ID, tblAgent.Naim,IIf([idinvoice]=" & k0dInvoise & ",""V"",""-"") AS Инвойс " & _
"FROM tblZakaz INNER JOIN (tblAgent INNER JOIN tblPostOrders ON tblAgent.ID = tblPostOrders.ida) ON tblZakaz.ID = tblPostOrders.idz " & _
"WHERE (((tblZakaz.ID)=" & k0dInvoise & "));" ' это просто пример подставите свой запрос
str2 = "0;Поставщик; Инвойс;"
strsql = str2 & ReSource( strsql)
Me.List57.RowSource = strsql
end sub