  The Higgs trilinear coupling $\lambda_{hhh}$ is of great importance to
understand the structure of the Higgs sector and allows searching for indirect
signs of Beyond-the-Standard-Model (BSM) physics, even if new states are
somehow hidden. In particular, in models with extended Higgs sectors, it is
known that non-decouplings effects in BSM-scalar contributions at one loop can
cause $\lambda_{hhh}$ to deviate significantly from its SM prediction, raising
the question of what happens at two loops. We review here our calculation of
the leading two-loop corrections to $\lambda_{hhh}$ in an aligned scenario of a
Two-Higgs-Doublet Model. We find their typical size to be 10-20% of the
one-loop corrections, meaning that they do not modify significantly the
one-loop non-decoupling effects, but are not entirely negligible either.
