Player Build Structure

Hey Community,
We are creating a persistent virtual world (multiplayer) which allows to build their structures on it using our player building system. The question here is that it’s a multiplayer game which is spread across multiple servers depending upon the location. So, how should we ensure that if a users builds a structure it’s visible across all the players (in other servers as well).

My next question is that when we release the updates of the game, how can we ensure that those structures are not deleted.

Also metaverses like Sandbox have so much user generated content but why’s that it’s total size is only 500mb?

Thanks in advance