  We present an extension of the GENEVA Monte Carlo framework to include
multiple parton interactions (MPI) provided by PYTHIA8. This allows us to
obtain predictions for underlying-event sensitive measurements in Drell-Yan
production, in conjunction with GENEVA's fully-differential NNLO calculation,
NNLL' resummation for the 0-jet resolution variable (beam thrust), and NLL
resummation for the 1-jet resolution variable. We describe the interface with
the parton shower algorithm and MPI model of PYTHIA8, which preserves both the
precision of partonic N-jet cross sections in GENEVA as well as the shower
accuracy and good description of soft hadronic physics of PYTHIA8. We present
results for several underlying-event sensitive observables and compare to data
from ATLAS and CMS as well as to standalone PYTHIA8 predictions. This includes
a comparison with the recent ATLAS measurement of the beam thrust spectrum,
which provides a potential avenue to fully disentangle the physical effects
from the primary hard interaction, primary soft radiation, multiple parton
interactions, and nonperturbative hadronization.
