I wouldn't be surprised if Half-Drow, being a subset of Half-Elf, is simply treated as Half-Elf. I would be pleased to be wrong, but idk if they'd go through the work to differentiate half-wood elf from half-high elf etc, while also being different from Elf. Basically, my theory is the top level "race" is what makes all the dialog differences.
Yeah, when meeting Shadowheart my half-Drow had the option to say “Two half-elves traveling together, maybe people will mistake us for cousins,†despite our conspicuously disparate heritage.
