At SDCC 2017, producer John Stephens confirms we all misunderstood the phrase "Harley Quinn is coming to Gotham". That phrase apparently meant: "Barbara is a little like Harley Quinn kinda."
"A recurring role, Maria Kyle is described as “a tough-as-nails operator with an arsenal of street smarts,” world-class drifter who’s able to hide her true self behind a variety of personas." By Matt Webb Mitovich for TVLine, 31 Oct 2016.