  The existing equivalence between (generalized) BMS Ward identities with
leading and subleading soft graviton theorems is extended to the case where the
scattering particles are massive scalars. By extending the action of
generalized BMS group off null infinity at late times, we show that there is a
natural action of such group not only on the radiative data at null infinity
but also on the scattering data of the massive scalar field. This leads to a
formulation of Ward identities associated to the generalized BMS group when the
scattering states are massive scalars or massless gravitons and we show that
these Ward identities are equivalent to the leading and subleading soft
graviton theorems.
