  Majorana neutrinos naturally lead to a Lepton Number Violation (LNV). A
superposition of Majorana states can mimic Dirac-type neutrinos, leading to its
conservation (LNC). We demonstrate on the example of specific observables
related to high and low energy processes how a strength of LNV correlates with
neutrino parameters such as CP-phases, flavor mixings, mass ratios. We stress
the coaction between low and high energy studies for putting phenomenological
models to a quantitative test. Secondly, we conclude that in order to fully
study the role of heavy neutrinos in search for New Physics (NP) signals, a
departure from trivial scenarios assuming degeneracy in mass and no flavor
mixing or CP-phases becomes necessary for a proper physical analysis.
