I would like to see integrations added for the mod mentioned in the title.
I confirm it is available for the latest Minecraft version at the time of writing.

About the mod

Link to the mod page (e.g. on CurseForge): https://www.curseforge.com/minecraft/mc-mods/rpg-hud

Link to mod source/API: https://github.com/KurodaAkira/RPG-Hud/tree/MC-Forge-1.16.5

What should be integrated exactly

Having blood bar of vampires integrated into hunger bar of the non-default huds (see green bar in screenshot).

I can help with testing to the extent my knowledge on modding can.

Additional comments

I now see this reported to rpg-hud as well. Raelzaryn/RPG-Hud#74