Gigi Hadid honors step-sis Marielle's birthday with touching throwback snaps

Gigi Hadid is celebrating her step-sister, Marielle's, milestone birthday! 

The Guest in Residence founder took to her Instagram Stories on Sunday, September 7, to pay a heartwarming tribute to her elder sibling on her special day. 

"Happy Birthday @mariellemama," Gigi began her birthday wish.

Zayn Malik's former flame continued, "Wishing my big sisty the most joyful and fulfilling year!!! She’s an amazing mama! Sister/auntie, cook/host/planner of all things fun and low-key, a comedian."

She concluded her post by telling Marielle how much she and her entire family “Loooove” their “Lead Hadid.”

Alongside the sweet homage, the mom-of-one dropped a never-before-seen picture of little Gigi sitting on the lap of her elder sister, seemingly the rare photo was taken in a restaurant. 

In another slide, Bradley Cooper's current love interest shared a snapshot featuring herself, her younger sister, Bella Hadid and Marielle.

She also included her only daughter, Khai Malik, in the frame, but she managed to keep her face hidden.

It is important to note that Gigi Hadid's father, Mohamed Hadid, shares his three children, Gigi, Bella Hadid, and his only son, Anwar Hadid, with his ex-wife, Yolanda Hadid, with whom he parted ways in 2000. 

In addition to Gigi, Bella, and Anwar, he is also a father to his elder daughter, Marielle Hadid, whom he co-parents with his second ex, Mary Butler, with whom he got separated in 1992.