Understanding the details of mass transfer in stellar binaries is often necessary to explain their observed properties. I will show how the outcomes of mass transfer from evolved red giants can explain the observed population of long-period compact subdwarf-B binaries if one correctly accounts for the metallicities of their progenitors. On a smaller scale, I will show that the outcomes of white dwarf-neutron star binaries may be understood if one correctly models mass loss in such binaries. The merging white dwarf-neutron star binaries lead to a variety of peculiar supernova-like transients. I will report on our recent work related to modelling the transients from such binaries, as well as on the exciting recent developments in merging double white dwarf binaries, leading, in particular, to type 1a supernovae and Ca-rich transients.
