[Answered ]-MultiForm Updateview Django

Your:

class SalleForm_avec_objet_adresse(MultiForm):
        form_classes = OrderedDict((
            ('salle', SalleForm_sans_objet_adresse),
            ('adresse', Adresseform),
        ))

should inherit after MultiModelForm instead of MultiForm.

http://django-betterforms.readthedocs.io/en/latest/multiform.html