multiple virtual ftp hosts

[axelvanmoorsel]

Hello,
I am running XAMP 7.1.7 on Debian 8, 64 bit, xfce interface.
I have created multiple virtual websites (9), some to maintain actual sites I created, and some for experimenting. One of these sites is what XAMPP creates when installing it. On two others I have installed Wordpress, because I want to learn to create Wordpress sites. I want to install new themes using FTP. FTP is working, because I can connect to the localhost using filezilla. But I can only connect to the XAMPP site, and not to the Wordpress sites. Is it possible to setup multiple virtual FTP hosts, just like you can setup multiple virtual web hosts?
Undoubtedly there will be other ways to install themes, but I want to create a site as similar as possible to an actual site.

Any help is greatly appreciated.