The superstar singer and husband have already introduced their twins, Moroccan Scott and Monroe, to the family tradition.
Ahead of Halloween, the fancy dress enthusiasts dressed up as comic strip heroes The Incredibles, with their six-month-old babies – nicknamed Roc and Roe – in matching outfits.
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The couple posted their personal album on a specially created site called Dembabies.com, in a reference to their pet name for them during the pregnancy.
"We deliberated for so long about how to reveal the first pictures of our babies to the world.
"We just didn't want to do the typical thing and display them in a tabloid (not that there's anything wrong with that).
"We decided to share this beautiful experience with you in a special intimate portrait of our family.
They added: "Parenthood is absolutely the most life changing experience we could ever have imagined.
"The love we feel for these babies is above and beyond anything we'd ever dreamed of."
In one impossibly cute shot, Roc lives up to his name with a toy microphone in his hand and a pair of sunglasses. In another, his sister, has been dressed up princess-style with a sparkly necklace and pearls.
The thrilled parents married in a secret wedding three years ago, after dating for just two months.
Shortly after tying the knot, the songstress told fans: "We really do feel we are soul mates. I never felt a love like this was on the cards for me."
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