AceShowbiz - Nicky Hilton taught new mom Paris Hilton how to change a diaper. The former "The Simple Life" star, 42, welcomed son Phoenix Barron, whom she has with husband Carter Reum, into the world via surrogate in January, and mother-of-three Nicky made sure her older sibling knew how to put a nappy on properly.

Speaking to the New York Post's Page Six column, Nicky, who has Lily-Grace, six, Teddy, five, and an 8-month-old son with her husband James Rothschild, said, "Paris was made to be a mom!" She then spilled, "I taught her how to change a diaper."

Gushing over her little nephew, Nicky gushed, "I'm obsessed with him." The 39-year-old beauty recently shared how Paris has been "on cloud nine" since becoming a mother.

She told PEOPLE recently, "She is on cloud nine. She is such an incredible mother. She was born to do this, and I'm just so happy for her". Nicky hopes her kids will be close to their little cousin once they finally get to meet him.

She added, "I'm just so excited for all the cousins and babies to be together. They haven't all met yet. When my kids have spring break in a few weeks, they're going to come here and meet their new cousin."

Paris recently revealed she has undergone further IVF treatment in a bid to have a second child - and she wants the baby to be a girl. In an interview with Glamour magazine, she explained "We've done it [the IVF process] seven times… I have all boys [embryos]. I have 20 boys."

The socialite then revealed the latest round of IVF took place earlier this year and they are waiting to see if it has been successful. Paris added, "I just went through the process again a month ago, so I'm waiting for the results to see if there's any girls."