You cannot use Relay on the same content as other sync services like Obsidian Sync, iCloud, Dropbox, or Google Drive. If these services compete over the same content, you are likely to get conflicts and data loss.
You can use multiple sync services in the same vault as long as they are working in different parts of the vault.
This is the same requirement imposed by any sync service, including Obsidian Sync.
The rule: no double coverage
Safe setup:
Use Relay for the shared project folders where you need true multiplayer
For everything else that you want to sync between devices, use whatever sync service you want, including Relay (just set up a separate Relay Server), Obsidian Sync, or iCloud, etc. If using something other than Relay, make sure to exclude the Relay-covered folders from this service
Double-check to make sure no folder or file is handled by both services
Dangerous setup:
Running a file sync service like Obsidian Sync on your entire vault, and running Relay on a folder within that vault ❌ (double coverage)
How to set this up safely
If you're adding Relay to a vault already synced by a device sync service like Obsidian Sync
Choose which folders will use Relay - typically project or team folders
Add those folders to your Relay Server as Shared Folders
Exclude those folders from your existing sync service:
If you use iCloud Drive, keep Relay Shared Folders outside iCloud-synced locations like Desktop, Documents, and iCloud Drive. Apple does not currently document a supported per-folder exclusion control for iCloud Drive; Apple's current guidance is to keep separate cloud services in separate locations on your Mac.
Check your sync service's documentation for folder exclusion steps
Relay does not recommend .nosync as the default setup: it is not exposed as a normal iCloud Drive setting, and renaming a folder can break paths you already use in Obsidian or other apps. If you choose to use it anyway, treat it as an iCloud-specific workaround you need to verify yourself on every device. The safer Relay setup is to put Relay Shared Folders somewhere iCloud is not syncing.
If you're not already using a device sync service
Consider using Relay for your entire vault
If you prefer two services, make sure to set up exclusions to abide by the 'no double coverage' rule:
Exclude your Relay Shared Folders from the new sync service before enabling it
Signs you have a sync service collision
The most common symptom is missing contributions:
You open a note that should have content, but it's blank
A note has reverted to an old version, losing recent changes
Content you or collaborators added has disappeared
You may also see Relay's conflict resolution banner asking you to resolve merge conflicts.
What to do if you're already in conflict
Stop the conflict immediately: Exclude your Relay folders from the other sync service
Check your files: Open shared documents and look for missing content or unexpected changes
If you see conflicts: Use conflict resolution and version history tools:
Use Relay's diff resolution tool, if presented.
Use Obsidian's built-in File recovery tool (independent of Obsidian Sync. See docs: https://help.obsidian.md/plugins/file-recovery)
If content is missing: Check if you have recent backups from before the conflict started. Use Obsidian's built-in File recovery tool (https://help.obsidian.md/plugins/file-recovery).
Why this happens
Different sync services use different approaches to handle simultaneous changes. When two services try to sync the same files, they can get overwrite each other's changes or create race conditions that result in data loss.
Each sync service assumes it's the authoritative source for your files. Running multiple services on the same content violates this assumption and creates unpredictable behavior.