Final state interaction in the $ {\mathrm{\Lambda }}_{b}\to {D}^{+}{D}^{-}\mathrm{\Lambda }$, $ {D}^{0}{D}_{s}^{-}p$, $ {D}_{s}^{+}{D}_{s}^{-}\mathrm{\Lambda }$ reactions

We study the three-body decays $ {\mathrm{\Lambda }}_{b}\to {D}^{+}{D}^{-}\mathrm{\Lambda },{D}^{0}{D}_{s}^{-}p,{D}_{s}^{+}{D}_{s}^{-}\mathrm{\Lambda }$, considering both internal and external emission mechanisms that produce various meson-baryon final states. Using a unitarized coupled-channel approach based on the local hidden gauge formalism, we analyze final state interactions in the exotic anticharm systems with strangeness $ S=-1$ and $ S=-2$. Significant threshold enhancements appear in both pseudoscalar and vector meson-baryon channels, indicating strong final state interactions and the possible formation of molecular exotic states below threshold. These features remain stable under variations of model parameters. Our results provide valuable insights into heavy hadron decay dynamics and offer theoretical guidance for future experimental searches of open-charm strange exotic hadrons. These results take into account the effects of the $ {D}^{+}\mathrm{\Lambda }$ and $ {D}^{+}{D}^{-}$ interactions, three-body rescattering, possible triangle singularities, parameter uncertainties, and large $ {N}_{c}$ behavior, making the predictions very reliable.