The idea is to enhance ProjectLink to allow the project manager to decide which project members can read (see) which part of the project and action items.
It may be sometimes necessary not to have full transparency. For instance in a new product development, you may work with two different suppliers who are competitors. You can already hide from each other the documents but as far as I know you cannot hide from each other their activities, status, action items or meeting (as well as their minutes) you organize with any of them.
One work around is to create a sub-project but I think this will overall improve efficiency if this could be managed in the same project.
You may want to group certain activities owned per the different suppliers into one summary activities and others into another one
Summary Activity : Quotation
Child Activity Supplier 1 : Quotation
Child Activity Suppluer 2 : Quotation
Summary Activity : Supplier Test results
Child activity supplier 1 Test results
Child activity supplier 2 Test results
I am refering to Windchill 9.1. Maybe PTC has already taken care of this in 10.1 but I have not been able to find that information thus my proposal as a new Product Idea.