We investigate heavy quark symmetries for heavy meson hadronic molecules, and explore the consequences of assuming the X(3872) and Z(b) (10610) as an isoscalar D (D) over bar and an isovector B (B) over bar* hadronic molecules, respectively. The symmetry allows to predict new hadronic molecules, in particular we find an isoscalar 1(++) BB* bound state with a mass about 10580 MeV and the isovector charmonium partners of the Z(b) (10610) and the Z(b) (10650) states. Next, we study the X(3872) -> D-0(D) over bar (0)pi(0) three body decay. This decay mode is more sensitive to the long-distance structure of the X(3872) resonance than its J/psi pi pi and J/psi 3 pi decays, which are mainly controlled by the short distance part of the X(3872) molecular wave function. We discuss the D-0(D) over bar (0) final state interactions, which in some situations become quite important. Indeed in these cases, a precise measurement of this partial decay width could provide precise information on the interaction strength between the D-(*)(D) over bar ((*)) charm mesons.