Scripting with XML logging, not appending file

Hi I'm using scripting of WINSCP with XML logging. The problem is that the file is overwritten each time it logs.
In the GUI I can see a button "append to file", is this option available with scripting?

Using version: 4.2.9

Command call:
"C:\Program Files (x86)Winscp\WinSCP.com" /script="D:\ftpscripts\ftp_getfilesWithMove.bat" /parameter /fromFolder/ D:\ToFolder\ *.xml /xmllog=D:\Log\Log.xml

The Script looks like:
option batch abort
option confirm off
open ftp://user:password@server:port -passive
cd %1%
lcd %2%
lpwd
get %3%
mv %3% ./Archive/
exit

Regards,
Rickard

You cannot append XML logs. If would create invalid XML.
You can create different log for every run with !T pattern:
https://winscp.net/eng/docs/ui_pref_logging