Book of Familiars is a simple mod that adds an item called the Familiar Book. This book allows players to store any tamed creature and release them anywhere in the world! Just left click your tame with the book in hand to store them. The "storage" is attached to the player, so the familiars will remain even if the book is lost. Includes config options to blacklist and whitelist mobs and for amount of creatures able to be stored.

All you need is a book, two iron ingots and two bones and you're good to go!

Mod compatibility:

The book by default checks if an entity is tamed and if the person trying to store the entity is the owner, so it should work for the majority of modded tameable creatures. If the mod has a more unique taming system in place, you may need to add the creature to the whitelist in the config. Keep in mind, this will make the entity storable without checking for an owner ID or if it's actually tamed. So, if you're playing on a server it means anybody can store it, even if they didn't tame it, and people can store other players tames.