Conway products and links with multiple bridge surfaces
  Suppose a link K in a 3-manifold M is in bridge position with respect to two different bridge surfaces P and Q, both of which are c-weakly incompressible in the complement of K. Then either   P and Q can be properly isotoped to intersect in a nonempty collection of curves that are essential (including non-meridional) on both surfaces, or   K is a Conway product with respect to an incompressible Conway sphere that naturally decomposes both P and Q into bridge surfaces for the respective factor link(s). 
Martin Scharlemann and Maggy Tomova