  We investigate heavy quark symmetries for heavy light meson-antimeson systems
in a contact-range effective field theory. In the SU(3) light flavor limit, the
leading order Lagrangian respecting heavy quark spin symmetry contains four
independent counter-terms. Neglecting $1/m_Q$ corrections, three of these low
energy constants can be determ1ined by theorizing a molecular description of
the $X(3872)$ and $Z_b(10610)$ states. Thus, we can predict new hadronic
molecules, in particular the isovector charmonium partners of the $Z_b(10610)$
and the $Z_b(10650)$ states. We also discuss hadron molecules composed of a
heavy meson and a doubly-heavy baryon, which would be related to the heavy
meson-antimeson molecules thanks to the heavy antiquark-diquark symmetry.
Finally, we also study the $X(3872) \to D^0\bar D^0\pi^0$ decay, which is not
only sensitive to the short distance part of the $X(3872)$ molecular wave
function, as the $J/\psi\pi\pi$ and $J/\psi3\pi$ $X(3872)$ decay modes are, but
it is also affected by the long-distance structure of the resonance.
Furthermore, this decay might provide some information on the interaction
between the $D\bar D$ charm mesons.
