Hi,
I'm working on a case where we want to have one parent business unit, and two child business units. Sell image below:

What we want to accomplish:
Users in business unit B should see all records in their own business unit, as well as those in business unit A.
Users in business unit C should see all records in their own business unit, as well as those in business unit A.
Users in business unit B and C should not see eachothers records.
Up to this point we have only had two business units, A and B, and therefore we could use Organization permission on a security role for the users in business B, however that wont work anymore as we will add another business unit. In addition, we cant use parent: child permission and set B and C as parents of A, because to my understanding we can only have one parent for a business unit.
Have anyone dealt with a similar scenario? What did you end up doing? Maybe there is someone that has any input on another way to deal with this scenario?
All the best