Speaking of, I would like to ask the community a question. Crimson Veil has now covered a wide variety of monster girls as enemies. Are there any obvious omissions that aren't in the game yet?
Let's see... It's naturally pretty hard to find openings for things like mermaids, but they could be particularly interesting if added as an enemy in the vampire route, as they're often seen as "good-aligned" monsters and it would be an interesting twist to see them treated as the victim to be corrupted into Mila's undead slaves. I've seen a bizarrely large amount of characters being redrawn as mermaids, but I don't think I've ever seen a mermaid get bitten and turned into a vampire... Of course, whoever it is that keeps commissioning the former would probably be disappointed if they didn't get to see Mila turned into a mermaid as well.
Harpies are another thing that's absent from the game, unless I'm mistaken. We do have what are essentially bat-harpies, but they feel like another part of the vampire theme. Having them portrayed as a sort of sweet songbird would be a stark contrast to their vampiric counterparts.
Of course, my contract submission was for a golem quest, although the ones in that contract would have been more of a sci-fantasy doll/robot/cyborg theme than the traditional "animated rock/clay statue" variety. Having the traditional variety show up wouldn't prevent my submission from still feeling unique (and it even assumed that Mila was already familiar with the concept of golems), so I don't even have a selfish reason to not want you to use them yet.
...Angels? If you don't already have an angel planned in a story role, giving vampire Mila the chance to corrupt one (or even giving regular Mila the chance to be "corrupted" by one) would be a natural fit.
Hmm... Arachne are fairly popular these days, but also despised by arachnaphobes. They do share a similar predatory vibe with vampires, so they wouldn't be out of place.
Those are all the ones that I can think of that would be a good fit. There's other stuff that doesn't fit as well outside of standard fantasy settings, like elves or fairies. And of course plenty of stuff that doesn't naturally have a female (or even humanoid) form but frequently gets redrawn as monster girls anyway.
Edit: And of course, as I mentioned a while back, there's room to further explore some of the ones that already appeared in the human route in the vampire route, having them be turned into vampiric hybrids that serve Mila and possibly being kept in a menagerie in Dorian's manor. Perhaps a sort of blood slime or a rose-and-thorns themed alraune that feeds with vampiric creeper vines.