  We briefly discuss how the chiral unitary approach in coupled channels and
$SU(3)$ symmetry can be used to describe the production of $f_0(500)$,
$f_0(980)$ and $a_0(980)$ in the $\chi_{c1} \to \eta \pi^+ \pi^-$ reaction,
recently measured by the BESIII collaboration. In this reaction a very strong
peak for the $a_0(980)$ can be seen in the $\eta\pi$ invariant mass, while
clear signals for the $f_0(500)$ and $f_0(980)$ appear in the one of
$\pi^+\pi^-$. Next, we show the predictions made with the same model for the
analogous decay $\eta_c \to \eta \pi^+ \pi^-$, which could also be measured
experimentally. We discuss the differences of these two reactions which are
interesting to test the picture where these scalar mesons are dynamically
generated from the interaction of pairs of pseudoscalars. Furthermore, we
comment on a new recent work where the same model was used to study the
$a_0(980) - f_0(980)$ mixing in the $\chi_{c1} \to \pi^0 \pi^0 \eta$ and
$\chi_{c1} \to \pi^0 \pi^+ \pi^-$ reactions, showing that quantitative
agreement with the experimental measurement of this mixing, also performed by
BESIII, can be obtained, revealing interesting aspects of the dynamics of this
process and the importance of coupled channels.
