It has been implemented already:
https://winscp.net/tracker/1358
https://winscp.net/tracker/1358
Session.SynchronizeDirectories
, where appending does not make sense.
public TransferOperationResult PutFiles(string localPath, string remotePath, bool remove = false, TransferOptions options = null, append = false)
...
WriteCommand(
string.Format(CultureInfo.InvariantCulture,
"put {0} {1} {2} -- \"{3}\" \"{4}\"",
BooleanSwitch(remove, "delete"), BooleanSwitch(append, "append"), options.ToSwitches(),
Tools.ArgumentEscape(localPath), Tools.ArgumentEscape(remotePath)));