  We provide a many-to-few formula in the general setting of non-local
branching Markov processes. This formula allows one to compute expectations of
k-fold sums over functions of the population at k different times. The result
generalises [14] to the non-local setting, as introduced in [11] and [8]. As an
application, we consider the case when the branching process is critical, and
conditioned to survive for a large time. In this setting, we prove a general
formula for the limiting law of the death time of the most recent common
ancestor of two particles selected uniformly from the population at two
different times, as t tends to infinity. Moreover, we describe the limiting law
of the population sizes at two different times, in the same asymptotic regime.
