Desktop Client Synchronization Confusion

I have been struggling with this for hours, I am hoping someone can provide help or an explanation of what I am doing wrong. I am NOT a computer person, so I am assuming I am doing something wrong.

On my local computer I have this directory structure (root is at the top):

/
|-A
|-B
|-C
##|----1
##|----2
##|----3
#####|—x
#####|—y
#####|—z

I have two Nextcloud servers, S1 and S2. For both I want to do a “one-way”, upload type of synchronization – that is, the server matches whatever is on the local computer (including the directory structure). The synchronization never changes anything on the local computer.

Using the Nextcloud desktop client, I have successfully synchronized the contents of the entire directory structure of directory C and all subdirectories within C with Nextcloud server S1. The path that I said to synchronize on the local computer is this: /C . Whenever there are changes on the local computer, this synchronization always successfully updates server S1 to reflect the changes on the local computer anywhere within /C. The directory structure on S1 mirrors what is on the local computer.
This synchronization works great.

Now, in addition I want to synchronize ONLY subdirectory z with Nextcloud server S2. I don’t know how to do that.

Using the Nextcloud desktop client, when it asks me the location on the local computer of the directory I want to synchronize, if I specify the path of /C/3/z, it won’t accept that: It provides an error message that says that the subdirectory is already part of another synchronization. I did not know what it was trying to tell me, my ASSUMPTION is that, because subdirectory z was already part of the synchronization with server S1, it would not allow me also to specify that subdirectory as the directory to synchronize with server S2. Is that a correct assumption?

So, I instead tried using this path again as I did with the server S1, and it accepted this: /C . Then, on the screen in the Nextcloud desktop client that shows the progress of the synchronization, I expanded the directory list under the connection for server S2, and unchecked subdirectories 1, 2, x, and y, and clicked the “apply” button. So, the only path that remained selected was /C/3/z . However, the client stubbornly uploads to server S2 EVERYTHING within /C . It seems to ignore the fact that I deslected those other subdirectories.

How do I go about (“one-way”) synchronizing all of /C with server S1, and also (“one-way”) synchronizing of just /C/3/z with S2?

I suppose that this is no doable. Since NC stores information about synced structures in couple of files in the top directory of the synchronization (i.e. “/C” in your case), it can’t be part of another sync.

You can try to create another directory (outside the synced structure), link the “/C/3/z” there and sync this one. But I didn’t test it an I’m not sure it will work.
Also I don’t know how NC handles symlinks during synchronization (if it follows them)

Thanks.

Nice thought, but your suspicion was correct. Here is the resulting error message:

“The local folder is a symbolic link. The link target is already contained in a folder sync connection. Please pick another one!”