Problem with formatting in code - column pasting

[Ace71425]

See code below.

Sub runallmacros()


    Dim wbSource As Workbook
    Dim wsDest As Worksheet
    Dim row As Integer, os As Integer
    
    Set wsDest = ThisWorkbook.Worksheets("File Copier")
    
    row = 2
    os = 0
    
    With wsDest
        Do While .Range("K" & row).Value <> ""
            Set wbSource = Workbooks.Open(wsDest.Range("K" & row).Value)
            wbSource.Worksheets(1).Range("A5:D500").Copy
            Application.DisplayAlerts = False
            wbSource.Close
            Application.DisplayAlerts = True
            If .Range("A1").Value <> "" Then os = 1
            .Range("A" & .Rows.Count).End(xlUp).Offset(os).PasteSpecial
            row = row + 1
        Loop
    End With
    
    Set wbSource = Nothing
    
End Sub

This code copies columns a-d of other tracking sheets...problem im having is it pasted to the next available A cell but if there is not data in A and data in B, C, or D it cuts off and overwrites that data. I need the code to reflect copy to the next available SET of cells based on the next available empty cell after searching through A, B, C and D. Thanks in advance!