  Three body heavy meson decays allows one to extract important quantities for
flavour physic, however the phenomenological analysis has some open problems to
be solved in order to make possible to extract physical parameters with
precision. After many years and some experience accumulated, we have learned
new features and we expect to learn much more from data coming mainly from B
three body decays. In this paper we address these aspects and we present a
proposal to modify the Dalitz fit amplitude method in order to allow further
studies.
