In this article, I describe multilingual interaction through the phenomena of formulation. It is studied as a collective work, developed in an incremental way, in which participants resort to a large variety of resources, verbal as well as gestural. The article is based on a corpus of multilingual interactions, with or without interpreters, recorded in consultations in mental and somatic health, with migrants and refugees, in France.In line with the DYLAN project's results, the paper shows the continuous work done by the participants on the linguistic resources, which blurs the boundaries between languages. It also reveals the impossibility to describe formulation processes, without including the gestural modalities.