with additional custom discussion

What would be the best way to add a second discussion in Plone, with different permissions and a different workflow?

Usecase: Alongside the regular discussion there should be an internal discussion on specific content items only, which is only available to users with a specific permission.

I can see that a Conversation object is initialized with a default id of ++conversation++default. Should I create a custom Conversation class?

I would take the KISS principle, auto-create a contained item and discuss there, everything else is view code then. Also much easier to deal with permissions then.

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