Feature Request: 1 item in more than 1 (shared) vault

I come upon this more and more often...

I have a shared vault where users A, B and C have access and I am the administrator/owner. I have another shared vault where users X, Y and Z have access and I am the administrator/owner.

I have an item that I need to share with all 6 of these users. I currently have 2 choices and I don't like either of them:

1/ Create a new shared folder where users A, B, C, X, Y and Z have access. This is fine in the cases of small teams. My situation however is a medium-sized business account with all of my clients in my umbrella/envelope account. Users A, B and C are not even aware of the existence of users X, Y and Z and may be uncomfortable sharing items with unknown users.

2/ Duplicate my item and store one copy in each of the shared folders. I dislike this option even more as maintaining the integrity of both copies is risky; there is always the possibility that one copy gets modified and the other does not.

Feature Request:
I would like to be able to assign/associate 1 item in more than 1 shared vault. The members of shared vault ABC do not need to see or be aware that the item is also in vault XYZ and vice-versa.

I am open to other ways of treating this problem/situation as well...

Thanks