abstract: An unfolding of a tangent to the identity diffeomorphism has an infinitesimal generator. It is possible to embed the diffeomorphism in the flow of Lavaurs vector fields by using auxiliary real flows of holomorphic vector fields. The Lavaurs vector fields are the natural candidates to be the sums of the infinitesimal generator in sectorial domains. We explain why it is necessary to consider more general transverse flows in order to prove the multi-summability of the infinitesimal generator in the parameter variable. We give some applications to the analytic classification of unfoldings.