I write Multiverse-Inventories. It offers an import feature to import data from MultiInv. Unfortunately what I wrote was forced to use reflection to break into your code to get the data I wanted. I would like to request that you expose your API in such a way that I can easily access all the data your store for your players. Thanks!

Fork MultiInv and add in the ability to import Multiverse-Inventories, then I'll add an API for you.