Penelope Scotland Disick made her worldwide debut on the August 20 Us Weekly cover– and now Kourtney Kardashian and Scott Disick‘s little girl is making her mark on the world!

In a series of  photos taken in Calabasas, Calif. The proud parents posed in their pajamas with their newborn daughter, 6 weeks,  and son Mason Disick, 2. “Nothing could prepare me for how hard I fell in love with her,” Kardashian, 33, raved of Penelope. “With Mason, we have such a love affair that I never knew existed. I didn’t expect it to happen again. It’s such a magical feeling.”

Like Mason’s birth in December 2009, Kardashian’s “delivery was really quick,” Disick, 29, recalled. “In the months before she gave birth, we would pray that she’d have a good one, and she did. Kourtney’s mother [Kris Jenner, 56] was very supportive. It was cute to see her hold Kourtney’s hand and get her through it.”

The couple isn’t sure if their daughter’s birth will be featured on one of the family’s reality shows. “We did tape it with our cameras, and Scott was taping some of it on his iPad,” Kardashian explained. “I could see cameras from all angles!”

When Mason came to the hospital to meet his younger sibling, “He was so excited,” Kardashian said. “He’s adjusting to everything so well. He calls her ‘sister.’ He gets mad if anyone calls her anything else. People will ask, ‘What’s your sister’s name?’ And he’ll answer, ‘Sister!” How Cute!

“He’s in love with her,” Kardashian added. “He’s always asking to hold her and cuddle with her.”

Ryu restaurant owner Disick has been a doting dad, “He’ll watch Penelope when I’m taking a shower, and when I put Mason down for bed, he’ll have time with Penelope and put her down for a nap. But he is not a diaper changer. I’ve changed every single one of her diapers so far.”

“My son is almost 3, and I don’t mind changing his diapers,” Disick countered. “I’m just not comfortable doing it when the baby is that small. One wrong move and you could break the child’s bone. At least my son can tell me, ‘Dad, you’re doing it wrong.’ With a little baby, it’s scary.”

Though Kardashian admitted to being moody while pregnant, she’s back to her old self. “Seeing her now, back in her normal mood, melts my heart,” Disick said. “She is happy, nice and energetic — all the reasons I fell in love with her.”