получение нового файла, добавленного к подверсии, не обновляя целую папку

Вы можете сделать что-то вроде этого:

Option Explicit

Dim originalRow As Range

Private Sub UserForm_Initialize()
    Set originalRow = ActiveCell.EntireRow '<< store this row in a global variable
    With Me
        .OriginalTourCode.Value = originalRow.Cells(1).Value
        .OriginalStartDate.Value = originalRow.Cells(2).Value
        .OriginalEndDate.Value = originalRow.Cells(3).Value
    End With
End Sub

Private Sub SplitTourCommand_Click()

    Dim ctrl As Control
    Dim wsSplits As Worksheet
    Set wsSplits = Sheets("Splits")
    Dim wsTours As Worksheet
    Set wsTours = Sheets("Final Tours")
    Dim WSheet As Variant
    Dim DTable As Variant, RowCount As Long

    'snipped autofilter code...

    With wsSplits.Cells(Rows.Count, "A").End(xlUp)
        .Offset(1, 0) = workOrderDescription
        With .Offset(2, 0).EntireRow
            .Cells(1) = OriginalTourCode.Text
            .Cells(2) = OriginalStartDate.Text
            .Cells(3) = OriginalEndDate.Text
            'etc etc for the other cells
        End With
    End With

    'no need to copy from the Splits sheet since you have the data
    ' in the form fields
    With wsTours.Cells(Rows.Count, "A").End(xlUp)
        .Offset(1, 0).Value = NewTourCode1.Text
        .Offset(1, 1).Value = NewStartDate1.Text
        .Offset(1, 2).Value = NewEndDate1.Text
        .Offset(2, 0).Value = NewTourCode2.Text
        .Offset(2, 1).Value = NewStartDate2.Text
        .Offset(2, 2).Value = NewEndDate2.Text
    End With

    originalRow.Delete 'remove the row the the split tour

    MsgBox "Tour " & ws.Cells(ActiveCell.Row, "A").Value & _
      " has been split to " & ws.Cells(ActiveCell.Row, "D").Value & _
      " and " & ws.Cells(ActiveCell.Row, "G")

End Sub