Two generator subgroups of free products with commuting subgroups

Let H and K be groups with respective subgroups U and V. Let F=H*K be their free product, R={[u,v];uset membership, variantU,vset membership, variantV} and N be the normal closure of R in F. Then the group G=F/N is called the free product of H and K with commuting subgroups U and V and is denoted by H*K/[U,V]. In the present paper we use geometric techniques of Kapovich and Weidmann to study 2-generator subgroups of free products with commuting subgroups. In the case where the factors are free and J is a two-generator subgroup then either J is free, or J=left angle bracketa,b[ap,bq]right-pointing angle bracket for some image of J is the fundamental group of a graph of cyclic groups where the underlying graph is either homeomorphic to a segment or a circle.