First, a side note: Datatables does not directly support nested tables. You’re going to need to do some work in JavaScript in your datatables definition to get the results you may be looking for.
Now, one way to do this would be to extend your get_data method in your model.
For example, if you want the prefix and description fields for all Projects associated with an instance of Ibv, you could add something like the following to your dict definition within the get_data method:
'projects' : [(project.prefix, project.description) for project in self.projects_set.all()]
(Note: I’m winging this, there may be an error in there, but hopefully it’s enough to give you an idea.)