How to set permissions for projects where only some issues are shared across those projects

[Mark Frampton]

I have two projects: "Internal Product" and External Client";

I want to share some issues across these projects, for instance issues in the Internal Product relevant to all;

But I want to restict External Client users to only see issues in the External Client project or public issues from the Internal Product project;

If I give External Client users the "Browse Projects" rights to the Internal Product project I can't seem to then filter the issues from the Internal Product project they see, when they go to the Internal Product project pages (it works fine seeing the shared issues in the External Client project for them)

I have set up two groups: Internal and All (ie the latter includes the Internal group and everyone else) and I tried to use Issue Permissions so that when an issue is created the reporter could determine who sees the issue but if I go in to the Internal Product project, as an External Client user,  I either can't access anything in the project or I can see all issues, depending on how I alter the permissions settings;

I also wanted to try a JQL query on the Internal Product project boards using currentUser() IN memberOf("Internal") to prevent External Client users from accessing any issues when they look at the Internal Product project boards but don't think that's possible;

Any suggestions on if this is possible and how to do it would be much appreciated.

Mark