(Pr)operads are generalizations of categories in which morphisms are allowed to have multiple inputs and multiple outputs.
In this talk we present a new family of algebraic structures that arise in the study of a class of functorial knot invariants. The main goal is the construction of a properad that arises in the study of welded braids. This is a preliminary result related to joint work with Dror Bar-Natan, Jonathan Beardsley and Zsuzsanna Dansco.