rsync to remote server running rsnapshot - how to prevent full duplicate?

I have a remote server A with rsync and ssh setup such that I can backup a group of machines (B, C, D and so on) to it securely.

Each machine's backups are in their own subfolder (/backup/B, /backup/C, /backup/D etc.)

Remote server A also runs rsnapshot daily, weekly, and monthly, so it has:-

/snapshots/
    daily.0
        B
        C
        D
    daily.1
        B
        C
        D

And so on for weekly.{0-4} and monthly{0-12}. Fairly standard.

The thing is, I have two FULL copies of all data from my other machines. There's a full copy of machine B's data in /backup/B and another full copy in /snapshots/daily.0/B

This seems inefficient, space wise. It would make more sense, to me, that daily.0 is just a symlink to /backup/B. Anytime the exteal machine runs a backup, it changes daily.0, and when remote server A runs rsnapshot daily, it does the normal rsnapshot thing (hard-link copy of daily.0 to daily.1 etc.)

Is this possible? I found this link - running rsnapshot with hardlinks only? which has zero answers, and the other rsnapshot results here at superuser do not seem relevant.

It seems like this would be possible by running rsnapshot from remote machines B, C, and D, but I'd prefer not to do that because I cannot rely on those machines being able to complete the rsnapshot process in one sitting. As it is, those machines run rsync when they can (and when their users remember), and a partial rsync just means a partial backup which can be fixed the next time rsync is run. Much more robust that way.

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