In the end, I wrote an api that can be called by the thirdparty module. I delivered the code to logon on django using c-code to this api and call the GET of this api. (using django rest framework). This api just saves the object (the id given in the url), and from there on it's default django. The only thing the third party had to do is build in my code to call the api as well....
Maybe not the best solution, but the best to implement for my problem....