"Mirror" without deleting files not in the database?

[RadicalDad]

New project, wondering if this is possible: I need to create a one-way sync (from an as-yet unspecified cloud repository) to a local machine. Changes in the cloud source - new, changed, and deleted files - need to be reflected on the local destination machines. Here is the tricky part: Files that show up in the destination local machine which never appeared in the cloud source must be left alone. They should not be deleted, which is what one would expect to happen if using exact mirror. Is there a way to implement this?

Use case: Source is hundreds (perhaps the low 1,000's) of sheet music files in a school setting. Destination is current and former student's local machines. Source files are constantly updated - new files, corrections and updates to existing files, and occasional deletes or re-names. These changes need to be reflected on student machines. However, the students regularly adapt these files for their own use, transposing the key for their own vocal range and making other personal adaptations. Students aren't particularly tech savvy, but are smart enough to create a new file for any changes they want to keep. The problem is not deleting those new files.

I suppose it might be possible for new student-created files to follow a naming convention that could be filtered and thus prevent the deletes, but recall I said that the students were not tech savvy. I'm afraid a restriction like this would doom the project to failure. It will already be a challenge to have the students learn to save their edits in a new file so they won't lose their work in the next sync. Storing the new files in a location separate from the "originals" would be highly undesirable for reasons I won't detail here.

Is this possible? What profile settings would I use to make this happen?

[superflexible]

Hello,
you can achieve this with the SmartTracking mode, and specify only one copying direction (such as Left to Right).

On the SmartTracking dialog, specify what should happen with deleted files.

Those files which have never been on the source side will not be touched on the destination.