Information sharing is problematic. Objective information is may or may not be valuable if it is not contextualized. Information sharing depends precisely on this relationship between information and context. When there are two stakeholders, two or more organizations, we wonder whether the necessity threshold should be used.
When you talk about what is strictly necessary, are we referring to relevance? Here, I'm sort of calling on the lawyer in you. How will that be managed?
An organization may consider a piece of information important and necessary, but the recipient may disagree. The opposite can happen. An organization may consider a piece of information only somewhat useful, whereas the agency with which it interacts is waiting for that information because its context, which the other organization cannot access, justifies it. In this case, the two thresholds for assessing the information seem problematic to me.