The 27-year-old singer is said to be "gushing" over pictures of her rumoured boyfriend's new nephew Quaid Robert Wise and shipped a bursting hamper to his home Toronto, Canada, to celebrate his arrival.
A friend of Derek's told The Sun newspaper: "Cheryl sent a beautiful basket of gifts when Quaid was born last week.
"She also sent Derek's sister a gorgeous note of congratulations along with the basket, which included a baby bath towel, teddy bears, dummies, an embroidered bib and organic bath products."
Derek's sister Sharee Hough Wise and her husband Randall Wise welcomed Quaid into the world earlier this month.
She wrote: "My new nephew!! RT @randallwise: Quad Robert Wise 7l bs 15 oz has arrived. We are blessed! (sic)"
Derek also shared his happy news with the world via the micro-blogging website, tweeting: "Wahoooo !!! I just got me a new nephew. Welcome to the world Quaid. (sic)"