Transferring sheet between different Multi-user Plans

I have a scenario where I want to transfer sheets from "Company A"  to "Company B" where both companies have their own multi-user plans.  

Specific Scenario

• "Sheet A" created/owned by "user A" in the "Company A" plan and thus stored within the "Company A" plan structure.
• "Company B" has their own multi-user plan of which "user B" is a licensed member
• Option 1:
  • Want to transfer "sheet A" so that it is stored within "Company B" plan but still owned by "user A"
• Option 2:
  • Want to transfer "sheet A" so it is stored within "Company B" plan and owned by "user B"

The reason for doing this is that sheets were started under "Company A" on behalf of "Company B" but now "Company B" has their own plan and wants to have all their sheets stored within their plan for backup and ownership purposes.

Are both of these options possible?  if so how do I do this?