Came across this Microsoft blog post by chance. To quote:
If the topology is set up for hub and spoke, and the spoke were to accidentally delete an item, this should not reflect back to the hub, correct? This should be a one way transfer. What we are seeing is our hub replicates out to the spokes perfectly, but if the spoke deletes an item, the item is then deleted from our hub share. It seems to be acting like a full mesh topology, but it was originally set up at as hub and spoke.
The behavior the customer describes is by design. Because DFS Replication is a multimaster replication engine, any change made on any spoke is replicated back to the hub and to the other spokes. To prevent changes from occurring on spokes, we recommend using shared folder permissions.
I too had always thought a hub-spoke design means the hub is the master server. But now I realize how wrong I was. Basically a hub-spoke or full mesh topology only determines the sync path – it does not denote which server is the master and which servers are slaves. DFSR, like AD, has no master or slave.
In a hub-spoke replication topology, two spoke servers will sync with each other via the hub server – that’s all! Neither server is “inferior” to the master in any way.