Share Vaults across accounts [Feature request]

I have a family account that I share with my wife and two kids.  My sister (let's caller Alice) has a personal account.  I have a friend (let's call him Bob) who has a personal account.  Let's call me Charlie.

My parents are aging and my sister and I have access to their bank account and are setting up automatic bill pay.  I would like to create a vault that Charlie and Alice can both see and edit that contains information about our parents.  I know that Charlie can invite Alice to become a member of the Charlie family plan and thereby give access to Alice, but in order to do that Alice must export all her current entries from Alice's-personal-account and then import them into Alice's-account-in-Charlie's-Family.  That's a hassle, and it also means that if Alice later marries and starts her own Family account, she'll lose access her parents' information housed in Charlie's Account's vault.

Charlie and Bob play squash and use SignUpGenius and a Gmail account to manage a Sunday doubles squash match with invitations that go out weekly to 50 players.  Bob travels a bit, and so does Charlie and they switch off the weekly duties of managing the interaction with SignUpGenius and Gmail.  Each has their own 1Password account, both have shared the SignUpGenius and Gmail credentials with each other, but both would like to be able to amend them.  Neither wants to be a member of the other's "family" for the purposes of 1Password, but they both want read/write access to the shared credentials. 

Request: please allow Vault sharing across paid 1Password accounts.  The sharing should allow transfer of ownership of the Vault from account A to B, from B to C, and from C back to A.  The sharing should allow the owner (A) to share with many people (each with their own paid accounts) B, C, D...etc. and should allow A to manage which parties can read, write, etc. the details in the shared vault.