  Uncertainty in the initial-final mass relation (IFMR) has long been a problem
in understanding the final stages of massive star evolution. One of the major
challenges of constraining the IFMR is the difficulty of measuring the mass of
non-luminous remnant objects (i.e. neutron stars and black holes).
Gravitational wave detectors have opened the possibility of finding large
numbers of compact objects in other galaxies, but all in merging binary
systems. Gravitational lensing experiments using astrometry and photometry are
capable of finding compact objects, both isolated and in binaries, in the Milky
Way. In this work we improve the PopSyCLE microlensing simulation code in order
to explore the possibility of constraining the IFMR using the Milky Way
microlensing population. We predict that the Roman Space Telescope's
microlensing survey will likely be able to distinguish different IFMRs based on
the differences at the long end of the Einstein crossing time distribution and
the small end of the microlensing parallax distribution, assuming the small
($\pi_E \lesssim 0.02$) microlensing parallaxes characteristic of black hole
lenses are able to be measured accurately. We emphasize that future
microlensing surveys need to be capable of characterizing events with small
microlensing parallaxes in order to place the most meaningful constraints on
the IFMR.
