I always enjoyed my head-canon:
.The 'last belmont', which I assume was Richter, learnt about Alucard and his extremely great granny hooking up since he was around to tell the tale
.In not wanting to kill his great grand-daddy Dracula and people already not trusting/fearing the belmont clan, put the curse behind him and give whip to Quincy family after post 18th century. Why? Dunno :p
.Dracula novel takes place in 19th century and Quincy Morris passed whip down to John Morris
.Bloodlines takes place and Portrait of Ruin take place
.Alucard finds Juilius in preparation for 1999 war and the curse continues
And yeah, I like to believe Legends and Lament of Innocence both happened.