In most cases, neutron stars and black holes seem to be accompanied by a brown or red dwarf if in a binary system. The rarest binary star arrangement I stumbled across once was a neutron star (or a black hole) with a main sequence F class star.
Has anyone ever found a multiple star with more than one stellar remnant? For example, binary white dwarf, BH+neutron star and so on? I cannot find any. Are systems such as these exceedingly rare or simply not generated?