In DC Comics, Harley Quinn doesn't have a daughter in the main continuity. Maybe in some alternate universe or spin-off? However, there's a character named Ivy in some stories, but that's not a daughter. So perhaps this is a fan-created scenario.
The structure of the query—using slang like "lil daughter" and concluding with "is old enough"—highlights specific search behaviors common on platforms like TikTok, Reddit, and X (formerly Twitter). Meaning / Intention harley sin lil daughter is old enough