When writing the plugin, make sure to add a friends system. So, obviously, friends from different islands can be allowed to edit blocks. Might require using an SQL server to store whether or not a player is a friend after logging off, I'm still learning about data storage with plugins.

 

I am really interested in why people don't support the idea of island protection. Does anyone have concrete proof that it lags the server or is that just want everyone tells each other accepting it as fact without checking its validity. I am not sure if you are aware, but the technology exists, the work has been done, and there are several servers out there that have a proof of concept that this can be done and it does work. If it doesn't cause any lag like people claim it to do, then we can protect the 10000+ islands without a problem. Members of the island can be automatically be added to the world guard permissions, you can setup a script to worldguard all of the islands since the math is super simple (49 from bedrock in all directions). For the people that didn't follow the rules on how big your island can be will just need to move their items into their island dimension. Even if we don't implement the worldguard protection, the contents outside of their island limit is always subject to not rollback capable and non-logged erasure from a new island so the person is always taking a risk having it there (hint hint you should move it if you care about it). So I guess my point is, that why not? Unless there is concrete evidence of the latency this plugin will cause, then what is stopping the server administrator or server owner?