Could you open local_root option

My FTP user account is chan, so I made a volume like `/data/a/chan:/home/vsftpd/chan`, it works perfectly, but I found out some of my client's code will use `../other` to put files to relative up folder, so I need to make a volume like `/data/a:/home/vsftpd/chan` and set `/data/a/chan` as default folder when login ftp, and also they can go up folder to other folder, is it possible?