Jessica Simpson's sister thinks she will make a "wonderful" mother.

The singer-and-actress got engaged to NFL star Eric Johnson last month and her younger sibling Ashlee Simpson-Wentz - who has two-year-old son Bronx Mowgli with husband Pete Wentz - can't wait for them to start a family.

She said: "She is genuinely very, very happy, and you go to their house and it's warm and cosy, and it's a good feeling. And he's just a good guy.

"Do I want them to have kids? Of course it would be wonderful if it happened. We were actually over there yesterday, and Jessica is a wonderful godmother, and aunt, so I know she would be a wonderful mother."

Ashlee is looking forward to celebrating Christmas with her husband and son and is enjoying the fact she and her family are creating their own special festive rituals.

She told People magazine: "For my husband and I, it's nice to start those traditions now. What we're doing with the tree, what we did over Thanksgiving. We actually had an amazing Thanksgiving with Peter's family."

However, the 26-year-old singer admits she is unsure what to buy Bronx for Christmas because he was given so many gifts when he turned two last month.

She said: "He just had his birthday, and he got a lot of gifts. He'll still have a great Christmas, and he's really into Thomas the Train, but we have enough Thomas, so we do not need that this year!"