I like to think that CotM happens out of the worst ending to SotN, in that Richter dies and Alucard goes back to sleep. Since Richter is dead but Dracula is still alive, the Morrises and Baldwins take up the Vampire Killer, rename it the Hunter's Whip, and continue the fight.
Oddly enough, if you think about it, OoE could still exist in the same timeline as CotM, as the Belmonts are gone as well and it deals with the remnants of the clan.