In (rare) cases it's necessary that bugs are shown as part of two or more projects.
That could be a bug in a project A, which only shows when project B uses project A.
Having such a report only in one project or even two different reports for the same problem will typically lead to a lower interest of this bug.
`ln -s` is your friend
then only an mail command for 'ln -s' is needed
> then only an mail command for 'ln -s' is needed
Probably all of this feature is too difficult to implement, for the
limited use it provides.