I’m thinking that I might be … you know … thick. 
I had actually read your article, Mattches, before posting my first query. It’s wonderful, and I understand it more or less completely, I think. Certainly the diagram, which is a 3-chain device, makes easy sense to me. Any change anywhere, propagates everywhere.
The problem for the thick one, who would be me, is that I do not understand how these devices came to have identical data in the first place. That is: How (specifically, in what order) were these devices initially chained? It seems to me that when the chain was created, none of the devices had identical data (possible, but it seems unlikely). Once they *have identical data, this seems easy. Any change, anywhere, gets propagated to every device on the chain. That much, seems like summing two-plus-two.
In my case, there will be only 2 devices. Maybe 3 later, but adding a third will introduce the same problem that my thickness doesn’t understand when creating even a 2-device chain … in which the data on the 2 devices does not initially match.
Which is the initial master, and which is the initial slave? I understand (or believe I do) that once “osmosis” has occurred
(data is identical), both/all devices are masters as well as slaves. They are masters at the moment any data is being added, altered, or deleted, because they will then cause the same to happen to other devices on the chain. The other devices have no say in this, so they are slaves, until such time as their data is changed directly by a user, and they then become masters, who “call the tune” for the entire chain.
But we have to get there, first. 
So, initially, assume a huge data imbalance, which will certainly be the case for me. Two devices. Let’s call 'em A and B. A is a worldly rogue of a browser. Lot’s of data. I mean, this bad boy has been around the block. B, however, is a trembling virgin. How do I chain them (this is good imagery, yes?)
so that B, during the initial copulation, does not wipe A’s memory of all worldliness, so to speak, but rather learns everything that A knows, instead? Once they are equal, it seems easy-peasy. But how to get there? Well, I’m thick, I guess.
Thanks for your help.