  Continuous variables multipartite entanglement is a key resource for quantum
technologies. This works considers the multipartite entanglement generated in
separated spatial modes of the same light beam by three different parametric
sources: a standard $\chi^{(2)}$ medium pumped by two pumps, a single-pump
nonlinear photonic crystal, and a doubly pumped nonlinear photonic crystal.
These sources have in common the coexistence of several concurrent nonlinear
processes in the same medium, which allows the generation of non-standard 3 and
4-mode couplings. We test the genuine nature of the multipartite entangled
states thereby generated in a common framework, using both criteria based on
proper bounds for the variances of nonlocal observables and on the positive
partial transpose criterion. The relative simplicity of these states allows a
(hopefully) useful comparison of the different inseparability tests.
