A small example of how to merge 2 files together.
Example
x=Join("C:\Test1.txt", "C:\Test2.txt")
Msgbox "Joined Successfully. NewSize of test2.txt is"+str$(x)
Function Join(strFile1 As String, strFile2 As String) As Long
Dim b() As Byte
Dim nFileNum As Integer
Dim lFileLen As Long
nFileNum = FreeFile
Open strFile1 For Binary Access Read As nFileNum
b() = InputB(LOF(nFileNum), nFileNum)
Close nFileNum
nFileNum = FreeFile
lFileLen = FileLen(strFile2)
Open strFile2 For Binary Access Write As nFileNum
Put nFileNum, (lFileLen+1), b()
Close nFileNum
Join = lFileLen
End Function