This basically confirms that: Warner Bros gave Gotham City Sirens to David Ayer and pitched a harley/joker movie, but Margot said no to both of them and started developing her own Birds of Prey movie instead.

Good Morning, Gotham!

I’ve been reading the old Paul Dini Gotham City Sirens comics and they’re a hoot! It’s the girls living together in this abandoned pet hospital so it’s like, Catwoman’s cats and Harley’s dogs and Ivy’s plants all jumbled together in domestic chaos :-D