2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/73068We obtain an upper bound for relative Dehn functions of amalgamated products and HNN--extensions with respect to certain collections of subgroups. Our main results generalize the combination theorems for relatively hyperbolic groups proved by Dahmani.Group Theory20F65; 20F67; 20E06text