When you upload documents to Mii-VAULT they are all stored in one centralised area so that you have all of the documents in one place. This is the Master Vault.

You can "Move" your documents within the Master Vault from one locker to another to make grouping them a lot easier. Simply click on the document, click on "Move" and then select the locker where you want to put the document.

In order for those documents to be available to other family members or to different lockers you need to assign them to those different locations. See the FAQ on "What does Assign a Document mean?"

When the document or media file is assigned to a locker or a vault it is still retained in the central store so that if you should ever delete or rename vaults and lockers you do not lose the original document.