  In this note we use the formalism of multi-KP hierarchies in order to give
some general formulas for infinitesimal deformations of solutions of the
Darboux-Egoroff system. As an application, we explain how Shramchenko's
deformations of Frobenius manifold structures on Hurwitz spaces fit into the
general formalism of Givental-van de Leur twisted loop group action on the
space of semi-simple Frobenius manifolds.
