The recent observation of the decay B 0 → Λc p̄ suggests that related decays may soon be visible at ee colliders. It is shown how these decays can shed light on strong final-state phases and amplitudes involving the spectator quark, both of which are normally expected to be small in B decays. PACS codes: 13.25.Hw, 11.30.Hv, 14.40.Nd, 13.75.Lb