Access to Plan Types in PJT

 Hi,

We have several plan types against a project but would like to restrict access to these plan types.  For example we have 5 plan types aganst the project, but one plan type that we would like only a specific responsibility to be able to update.  The other four should not be updateable. 

Currently we have a user responsibility that allows update but this is for all plan types against the project.  Another responsibility allows only inquiry access.  We want to be able to tailor the access based on the plan type.

Any ideas how we could achieve this?

Thanks

David