  We show how to obtain a ``heavy'' meson effective lagrangian for the case
where the number of heavy particles is not conserved. We apply the method in a
simple example at tree level and perform then the reduction for the case of
vector mesons in Chiral Perturbation Theory in a manifestly chiral invariant
fashion. Some examples showing that ``heavy'' meson effective theory also works
at the one-loop level are included.
