Combination of convergence groups

We state and prove a combination theorem for relatively hyperbolic groups seen as geometrically finite convergence groups.For that, we explain how to contruct a boundary for a group that is an acylindrical amalgamation of relatively hyperbolic groups over a fully quasi-convex subgroup.We apply our result to Sela's theory on limit groups and prove their relative hyperbolicity.We also get a proof of the Howson property for limit groups.