  We revisit the formation of pion-mediated heavy-light exotic molecules with
both charm and bottom and their chiral partners under the general strictures of
both heavy-quark and chiral symmetry. The chiral exotic partners with good
parity formed using the $(0^+, 1^+)$ multiplet are about twice more bound than
their primary exotic partners formed using the $(0^-,1^-)$ multiplet. The
chiral couplings across the multiplets $(0^\pm, 1^\pm)$ cause the chiral exotic
partners to unbind, and the primary exotic molecules to be about twice more
bound, for $J\leq 1$. Our multi-channel coupling results show that only the
charm isosinglet exotic molecules with $J^{PC}=1^{++}$ binds, which we identify
as the reported neutral $X(3872)$. Also, the bottom isotriplet exotic with
$J^{PC}=1^{+-}$ binds, which we identify as a mixture of the reported charged
exotics $Z^+_b(10610)$ and $Z^+_b(10650)$. The bound isosinglet with
$J^{PC}=1^{++}$ is suggested as a possible neutral $X_b(10532)$ not yet
reported.
