I wish to adopt (simple adoption) the adult children of my wife. I have adult children myself, born from a previous union. Do they have to consent to this adoption ?

No. When the adopter himself has children, the court called upon to rule in regard to the adoption verifies that it is not likely to compromise family life (art. 353, para. 3 C. civ. by 361 reference). However, as part of the documents which need to be provided in support of the request (cerfa 15741), the opinion of the adult children of the adopter must be present. The scope of this opinion is limited, the decision to pronounce or not the adoption being the responsibility of the judges .