How to share specified folders between three devices?

Question

Android

There is a desktop on wine 7, a laptop on wine 7 and smart on android 4.2. On the desktop, there are folders and files in various places that you need to have access to from two other devices (the ability to update files, add new files to selected folders, etc.). The main condition: the folder structure on the desktop should not be changed: for example, scripts on one disk, financial reporting files on another. That is, everything must be implemented in such a way that it is not necessary to move all synchronized data to one directory (as Dropbox requires, as far as I understand).
Synchronization must occur over the Internet.
What and how can this be done?

Answer 1

I can suggest using symlinks (Symbolic Link).
1) If Dropbox does not work with them: transfer everything to Dropbox, and on the desktop in the old place, create a symlink to the folder in Dropbox.
It turns out that everything lies along the old path (symlink), and is synchronized in Dropbox (original files).
But there may be problems with other applications through which you will work with files along the old path - they may not understand symlinks.
2) If Dropbox understands symlinks, then you can do the opposite: create a symlink in Dropbox.
If symlinks do not work, then Junction Point can be created.

Answer 2

BitTorrent Sync

Answer 3

Any cloud storage, I have all 3 (that I use) work correctly
Working documents are on the Yandex cloud.Disk
Personal photos are on the 100 GB cloud from Mail
Projects are on Google Drive