Question about ftp login/session

[medelin]

Hello,

I have question about Ispconfig 3, on debian, with pure-fpdd.

I noticed that I add sites via ispconfig3 panel, and create ftp acconts for users, ispconfig does this way: owner=sitename (webX) group=client (clientX).

So, when I eg. create 50 sites via panel, to upload data into them I need to create 50 separate ftp accounts also ?

Or maybe there is possibility to log in as user/client and upload content to each directory in one ftp session ?

If so (will be different sites), what about uploaded files owner/group ?