The problem:
You need to send bugs (bug data & attachments) to somebody who does not have direct access to the Bugzilla server at all. Then you need to upload updates on bug status, comments, etc from this external party to Bugzilla.
In other words you need to setup a sync between a Bugzilla Database and a Deskzilla client on a file basis.
Solution
The solution will require a proxy person (P) with access to Bugzilla and installed Deskzilla, who will be exchanging data with the external user (U), who has no access to your Bugzilla, but has Deskzilla installed.
...