It would be great if we could assign users of such third party companies to multiple organizations.
When they open a ticket they could choose for which company they want to create their ticket. The managers of the implicated clients could see and manage these tickets from the portal.
We're pleased to share that this ability has been added to Deskpro. You can now create Users that are associated with more than one Organization. You can find out more about this update here: https://support.deskpro.com/en-US/news/posts/deskpro-horizon-release-202338#new_features