  We study the $\bar B^0_s \to J/\psi K^+ K^-$, $\bar B^0 \to J/\psi K^+ K^-$,
$B^- \to J/\psi K^0 K^-$, $\bar B^0 \to J/\psi \pi^0 \eta$ and $B^- \to J/\psi
\pi^- \eta$ decays and compare their mass distributions with those obtained for
the $\bar B^0_s \to J/\psi \pi^+ \pi^-$ and $\bar B^0 \to J/\psi \pi^+ \pi^-$.
The approach followed consist in a factorization of the weak part and the
hadronization part into a factor which is common to all the processes. Then
what makes the reactions different are some trivial Cabibbo-Kobayashi-Maskawa
matrix elements and the weight by which the different pairs of mesons appear in
a primary step plus their final state interaction. These elements are part of
the theory and thus, up to a global normalization factor, all the invariant
mass distributions are predicted with no free parameters. Comparison is made
with the limited experimental information available. Further comparison of
these results with coming LHCb measurements will be very valuable to make
progress in our understanding of the meson-meson interaction and the nature of
the low lying scalar meson resonances, $f_0(500), f_0(980)$ and $a_0(980)$.
