  We describe a chiral formalism for processes involving both energetic hadrons
and soft Goldstone bosons, which extends the application of soft-collinear
effective theory to multibody B decays. The nonfactorizable helicity amplitudes
for heavy meson decays into multibody final states satisfy symmetry relations
analogous to the large energy form factor relations, which are broken at
leading order in Lambda/mb by calculable factorizable terms. We use the chiral
effective theory to compute the leading corrections to these symmetry relations
in B -> M_n pi ell\bar\nu and B -> M_n pi e+e- decays.
