  In general, resonances are obtained by the Breit-Wigner parameterization.
However, it is not entirely appropriate to use this parameterization with
near-threshold resonances such as the $Z_b(10610)$ and the $Z_b(10650)$, as
Breit-Wigner does not contain the threshold effect. To eliminate this defect, a
recently proposed alternative distribution, the Sill, is used to predict
possible heavy quark spin symmetry partners of the $Z_b(10610)$ and the
$Z_b(10650)$. With the Sill values of the $Z_b(10650)$ and the $Z_b(10610)$
states, assuming these exotics generate molecular states consisting of contact
and a pion exchange potential, heavy quark spin symmetry partners are examined
with $S$ and $D$-wave contributions. In the light of the Sill type resonance
approach, all the partners are found as bound states.
