I wonder if the daughter who died of old age was infertile. Even so, fostering and adoptions exist. These vampires did it for her, after all. And it's not like they're replacing her.
Also, when they're mourning her it comes off as rather self indulgent. It's all about them and how they are suffering. We get these abrupt, isolated montages of this girl's life. Just her at various stages in age. Nothing about how it was a blessing that they got to have this child in their lives.
Did they even give her a good life? Allowed her to do as she wished and was there for her? We don't know, it's never shown. Considering their narcissistic navel-gazing throughout the entire story beyond this arc I seriously highly doubt it.
My other problem with this story is that they're immortals who don't do anything but whine about how bad it is to live forever. They don't even try to find meaning in life. Always superficially partying and then wallowing in their own romantic self pity when that gets old.
Why didn't they become scientists? Even if they're not naturally curious or scientifically minded. If I had immortality you'd best believe I'm gonna research aaaall the ways to end cancer and other diseases.
I mean, even if they're selfish assholes who don't care about how healthy their playthings are shouldn't they at least want to know how they came about? What makes them function?
They're gorgeous but shallow parasites who refuse to learn how to contribute to the world they feed off of.
I still gave it a 5 anyway. I'm a shallow bitch and the artwork is still stunning even if the story nearly made me roll my eyes out of my head.