Single viewpoint with specific permissions for each branch?

Summary:

Is it possible to have multiple users that edit their own branch within a single viewpoint?

Content (required):

Our requirement is that different users are responsible for editing a specific hierarchy (i.e. Product) , each of them working on a specific branch in that hierarchy (i.e. Product type A, Product type B, ...). Is it possible to let the users to view the full hierarchy but edit only their specific branch, using just one single full viewpoint (i.e. Product).

Or the only possibility is to create the viewpoint Product to ensure read over the full hierarchy and create N additional viewpoints for the edit needs, one for each users/branches. In this case I guess subscriptions are required in order to maintain in sync the "master" viewpoint and the other N "sub" viewpoints.