If cell is empty copy line x times and fill the blanks with predetermined text

Hello - I am fairly new to VBA so appreciate any help or guidance. Thank you

I have 4 columns of data where the random blank in col C signify condensed lines. The creator wanted to reduce the # of lines so saw the pattern repeated in this cell and ignored it and removed the duplicates and said the blank represents D1,D2,D3,D5,D7,D8. I need the duplicates re-instated and these values added back in.

and I need quick way to transform the data and expand the condensed form that where finds an empty cell in column C - duplicates/copies that row 5 times making a total of 6 lines and then adds/fill each blank cell with the 6 unique text value (i.e D1,D2 etc.) and then repeat until all blanks have been expanded back out from approx. 2000 lines of data to 8000.

COL INT LEX PV
345000 A 3654898
258000 C D2 6987450
258000 C D5 6987450
258000 C D7 6987450
103698 D 8521030

According to your attachment as a VBA beginner starter :

PHP Code: 

Sub Demo1()
    Dim R&, V, U&, Rw As Range, N&
        R = 1
        V = Sheet5.UsedRange.Value2
        U = UBound(V) - 1
        Application.ScreenUpdating = False
    With Sheets("desired_results")
            .UsedRange.Clear
        For Each Rw In Sheet4.UsedRange.Rows
            N = 1 - IsEmpty(Rw.Cells(3)) * U
            Rw.Copy .Cells(R, 1).Resize(N)
            If N > 1 Then .Cells(R, 3).Resize(N) = V
            R = R + N
        Next
    End With
        Application.ScreenUpdating = True
End Sub 


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Thank you for providing this solution - Its exactly what I needed - much appreciated