Merging multiple worksheets into one workbook from a list

[allenayres83]

The code below merges some excel templates into a single workbook from a list on my "Data" worksheet and fills out some header information that also comes from "Data". This data can be updated from time to time and new items added to the list. Some of the information in the old items can be updated also. Can this code be modified to only merge in the new items that were added to the list and update the header information on all old and new worksheets.

Enum ReadColumns
    rcLineItem = 2
    rcItemCode = 3
    rcUnits = 6
    rcSupplementalDescription = 4
    rcUnitPrice = 5
    rcOriginalPlanQuantity = 7
    rcCurrentPlanQuantity = 8
    rcCategory = 1
End Enum
Sub MergeandFillHeader()
    Dim v As Variant, i As Long
    Dim wb As Workbook, n As Long

    With Application
        .ScreenUpdating = False
        .Calculation = xlAutomatic
    End With
   
    With ThisWorkbook
        v = .Worksheets("Data").Range("C11").CurrentRegion.Value
        For i = 3 To UBound(v)
            If Not v(i, rcItemCode) = vbNullString Then
                Set wb = Workbooks.Open(.Worksheets("Merge").Range("D5").Value & "\" & v(i, rcItemCode) & ".xlsm")
                wb.Sheets(1).Copy After:=.Sheets(.Sheets.Count)
                With .Sheets(.Sheets.Count)
                    .Cells(1, 4).Value = Worksheets("Merge").Range("D3").Value
                    .Cells(2, 4).Value = v(i, rcItemCode)
                    .Cells(3, 4).Value = v(i, rcCategory)
                    .Cells(4, 4).Value = v(i, rcLineItem)
                    .Cells(5, 4).Value = v(i, rcSupplementalDescription)
                    .Cells(6, 4).Value = v(i, rcUnits)
                    .Cells(7, 4).Value = v(i, rcOriginalPlanQuantity)
                    .Cells(8, 4).Value = v(i, rcCurrentPlanQuantity)
                    .Cells(10, 4).Value = v(i, rcUnitPrice)
                End With
                n = n + 1
                wb.Close False
            End If
        Next i
    End With
   
    With Application
        .ScreenUpdating = True
        .Calculation = xlCalculationAutomatic
    End With
   
    MsgBox "Processed " & n & " files", Title:="Merge Excel files"
End Sub