  Subensemble Acceptance Method (SAM) [1,2] is an essential link between
measured event-by-event fluctuations and their grand canonical theoretical
predictions such as lattice QCD. The method allows quantifying the global
conservation law effects in fluctuations. In its basic formulation, SAM
requires a sufficiently large system such as created in central nucleus-nucleus
collisions and sufficient space-momentum correlations. Directly in the spinodal
region of the First Order Phase Transition (FOPT) different approximations
should be used that account for finite size effects. Thus, we present the
generalization of SAM applicable in both the pure phases, metastable and
unstable regions of the phase diagram [3]. Obtained analytic formulas indicate
the enhancement of fluctuations due to crossing the spinodal region of FOPT and
are tested using molecular dynamics simulations. A rather good agreement is
observed. Using transport model calculations with interaction potential we show
that the spinodal enhancement of fluctuations survives till the later stages of
collision via the memory effect [4]. However, at low collision energies the
space-momentum correlation is not strong enough for this signal to be
transferred to second and third order cumulants measured in momentum subspace.
This result agrees well with recent HADES data on proton number fluctuations at
$\sqrt{s_{NN}}=2.4$ GeV which are found to be consistent with the binomial
momentum space acceptance [5].
