[Answered ]-How can I use multiple queryset in a ModelChoiceField?

You can have 2 different selects One for politic and one for economic and show/hide them based on choice field.

Or maybe Abstract Model Inheritance would solve your problem

One possibility would be to use a Generic Relation in your Catagory model.

Thanks for your answers, I try to use your two solutions (Abstract Model and Generic Relation) but it doesn’t resolve my problem.
So I create two differents ModelChoiceField (one for Politic and one for Economic) and I use hide/show effects of Jquery in my template (like you say Kugel).
But if you have any others ideas for my problem, I’m interessed.