White dwarfs (WDs) are the endpoint of evolution for 97% of stars. Most of these stars are in multiple systems, and a significant fraction of those are compact enough to exchange mass, altering the structures and subsequent evolution of both stars. The physical mechanisms that facilitate these mass exchanges include common envelope evolution, Roche lobe overflow, wind accretion, mass stripping, and stellar mergers. All of these processes are poorly understood, leading to substantial uncertainties in the evolution and final outcomes of multiple star systems. These uncertainties impact various astrophysical problems, ranging from the occurrence rates of novae and cataclysmic variables, to modeling extragalactic stellar populations and establishing the formation rates and delay time distributions of important transients such as Type Ia supernovae and the progenitors of gravitational wave sources now observable in the LIGO and LISA passbands. The primary goal of our project is to advance the understanding of mass transfer processes in interacting systems by assembling a unique observational sample of thousands of post-mass-transfer binaries. Our sample combines data from the GALEX and Gaia databases with data from the SDSS APOGEE survey to create a census of post-mass-transfer binaries containing WDs with main sequence, subgiant, red giant, and red clump companions. We are currently augmenting this rich dataset with TESS light curves and additional radial velocities from the WIYN and Las Cumbres Observatory telescopes to increase the number of systems with reliable orbital solutions. This will yield a unique archive that includes not only derived properties (luminosities, temperatures, chemical compositions, radii, etc.) of the component stars, but also the binary system architectures (period, separation, masses, eccentricities) for thousands of systems. This comprehensive dataset will enable us to perform multivariate statistical analyses to characterize multiple intermediate stages in the evolutionary path between main sequence binaries and post-mass-transfer systems. Additionally, we will explore systematic trends with stellar parameters such as mass and chemical composition and provide a solid observational framework to benchmark binary population synthesis codes. The authors gratefully thank funding from the National Science Foundation (NSF) under Award AST-2307862.