  We present a novel framework capable of addressing the dark matter problem
through freeze-in and freeze-out mechanisms, separately or together, depending
on the region of the parameter space considered. In the dark matter dynamics,
the model features an interplay of thermal production along with sizeable
contribution through feeble decay of associated dark fermionic partner, which
finally freezes out to the right relic density for a wide range of masses and
couplings. Apart from the fermionic dark matter candidate, the model introduces
two charged partners, one fermionic and another scalar, which often have
delayed decays leading to distinct characteristics of such long-lived particles
(LLP) in the colliders like the LHC. Our analysis shows that within the present
scenario, LLP of decay length that could be probed at the LHC experiments are
compatible with dark matter masses ranging from a few GeV to close to a TeV, as
opposed to the requirement of keV-MeV dark matter in simple FIMP scenarios with
LLP. In addition, the model presents hitherto unexplored interesting
possibilities in the LLP searches, like (i) LLP to LLP to SM cascade decays,
which could be searched for within the LHC detectors and (ii) heavy neutral
particle decaying within MATHUSLA with two jets and large missing energy. A
supplementary aspect of the model is the presence of a heavy neutrino
facilitating Type-I seesaw mechanism without disturbing the dark matter side.
