Credit: Ramey Photo

There are no secrets between partners!

Chris Meloni knew all along that his Law and Order: SVU costar Mariska Hargitay was planning to adopt. "She was a little 'stressy stressy,'" the actor, 50, told Thursday night in New York at the Food Bank for New York City's Can-Do Awards.

Hargitay, 47, and husband Peter Hermann, 43, recently adopted a baby girl and named her Amaya Josephine, the star's rep confirmed Wednesday night to Us.

"Uh, yeah [I knew she was adopting!] I'm her partner," he said. "You didn't know; I knew. I had to keep my mouth shut."

Meloni, who has two kids of his own with wife Sherman Williams (Sophia, 11, and Dante, 7) said Hargitay was "going to be great" with her family's new addition. "She's a woman that possesses a lot of love. She's extraordinarily intelligent. I think she understands human behavior. She has endless patience."

Hargitay gave birth to son August, 4, back in June 2006. Her rep told Us: "The couple are overjoyed by the wonder of their new daughter." A source added that the adoption "was a long time coming."

So what did Meloni give to the newest member of the SVU family? "I haven't figured out what [to get] yet! I'll have to get back to you. You want to make it unique -- not a cliche."