Merge Empty Data

MDMorse 

Here is a macro you can run. Please test on a copy of the worksheet!

Sub MergeRows()
    Dim s As Long
    Dim m As Long
    Dim t As Long
    Dim c As Long
    Dim vs As Variant
    Dim vt As Variant
    m = Range("A" & Rows.Count).End(xlUp).Row
    vs = Range("A1:D" & m).Value
    ReDim vt(1 To m, 1 To 4)
    For c = 1 To 4
        vt(1, c) = vs(1, c)
    Next c
    t = 1
    For s = 2 To m
        If vs(s, 1) <> vs(s - 1, 1) Then
            t = t + 1
            For c = 1 To 4
                vt(t, c) = vs(s, c)
            Next c
        Else
            vt(t, 3) = vs(s, 3)
        End If
    Next s
    Range("A1:D" & m).Value = vt
End Sub