  Using the new set of dd --> eta alpha near threshold experimental data, the
estimate of the importance of the nucleon-nucleon correlations for the eta
alpha S-wave scattering length in the multiple scattering theory is obtained
using the low-energy scattering length model. The contribution turns out to be
much bigger then previously believed. The pi-eta mixing angle is extracted
using the experimental data on the dd --> eta alpha and dd --> pi alpha
processes. The model is dominated by the subthreshold extrapolation recipe for
the eta alpha scattering amplitudes. When the recipe is chosen the model is
completely insensitive to the eta alpha parameters for the subthreshold value
of the eta cm momentum of p_{eta}^2 = -(0.46)^2 fm^{-2}. Provided that the
subthreshold extrapolation recipe is correct, a good estimate of the pi-eta
mixing angle is obtained, if the experimental cross sections for the dd --> pi
alpha reaction at the corresponding deuteron input energy are taken from the
literature.
