Hola, Pablo.
> I need to add a method to a Form that is part of a Formset.
>I can´t find a way to do that, because all the new Methods I have created were placed in the formset, not the form.
You have to save this form as a class. Then, open the form in the class designer and add the methods you need.
Finally, go back to your formset, remove the form, and add it again, but as an instance of your new class.
Please, tell me if you understood this.
Hope this helps,