  We discuss the range of validity of ChPT when applied to the systems of
heavy-light mesons. Having in mind the recent experimental evidence according
to which the heavy-light scalar and axial states are closer to the ground
states than anticipated, we revisited the prediction for the chiral behavior of
the B-Bbar mixing amplitude and examined the impact of nearness of the positive
parity states. We conclude that the standard ChPT expressions with Nf=3 light
flavours are not useful in guiding the extrapolation of hadronic quantities
computed on the lattice. Instead those derived in HMChPT with Nf=2, i.e.,
including only the pion loops, are still adequate as long as they are applied
to the pions lighter than 350 MeV, or the quarks lighter than a third of the
physical strange quark mass.
