Yes, you can
Change file names to suit:
Option Explicit
Sub EditTextFile()
Dim newline As String
Dim strline As String, strarr As Variant, i As Long, pos As Long
newline = "String to be added"
pos = 3 '<--position to insert the new line, zero based, change to suit
Open "C:\MyFolder\fatty.txt" For Input As #1: strline = Input(LOF(1), 1): Close #1
strarr = Split(strline, vbCrLf)
Open "C:\MyFolder\fatty1.txt" For Output As #1 '<--temporary file name
For i = 0 To UBound(strarr) - 1
If pos <> i Then
strline = strarr(i)
Else
strline = newline & vbCrLf & strarr(i)
End If
Print #1, strline
strline = ""
Next
Close #1: Kill "C:\MyFolder\fatty.txt"
Name "C:\MyFolder\fatty1.txt" _
As "C:\MyFolder\fatty.txt"
End Sub
~'J'~