One of our pack developers has created a mod to help with the creation and managing of islands. The mod is only needed on the server-side, so you do not need to install it on your client install.
We have included this mod for you already with these server files.

Note: If you need it for your client for single player installs use read below.
- You can download the mod via: https://github.com/sam-kirby/topoislands/releases Once downloaded just drop the mod into the mods folder on the server.

The list of commands are as followed:
/topoislands new <PLAYER_NAME>
- Can be executed by OPs and creates a new island, teleporting the named player to it.
/topoislands assign <PLAYER_NAME> <ISLAND_ID>
- Can be executed by OPs and assigns a player to the island given. It teleports the named player there.
/topoislands info
- Prints details about the player's current island - its ID and coordinates.
/topoislands spawn
- Takes a player to spawn.
/topoislands home
- Takes a player to their assigned island.
/topoislands invite <PLAYER>
- This can be run by any player who is assigned to an island and allows them to invite another player to their island without intervention from an op.
- The invitee can accept the invite by clicking the link in chat, or by running /topoislands accept

Info: The "new" and "assign" command can be triggered via command-blocks if you want to go that direction.

If you encounter any issues with the mod or the commands be sure to log an issue to https://github.com/sam-kirby/topoislands/issues

Also, send your thanks to Sam for the amazing mod! <3