Hilary Duff's fiance has had a tattoo in honour of their daughter and her son

Matthew captioned the black and white photo: "Luca (7) and Banks (1) holding hands just after her 1st birthday. Thank you @curtmontgomerytattoos for engraving my kids.(sic)"

Last month, the 'Lizzie Maguire' star laughed off speculation she had secretly married the 32-year-old songwriter - who she got engaged to in May - after he referred to her as his "wife" on Instagram.

She said: "No, we are not secretly married, but we are basically married, so you know, sometimes those little things slip out."

The blonde beauty insisted that when they do get married she wants both Banks and Luca to be there and admitted their parents would be annoyed if they went off and eloped.

She admitted: "We're really excited and we're torn between, 'Are we just going to go to the chapel and do it?' or 'Are we going to have a little more thought put into it?'

"I think our families would kill us [if we eloped]. And we want the kids to be involved."

When Matthew proposed, he presented the 33-year-old star with a book of their memories together and had the ring hidden inside.

She previously shared: "I came home from work on a random Tuesday. And he's like, let's go for walk, let's go check out this park. And we were living in Williamsburg, and I was like I'm so tired. I just want to eat dinner in bed and watch 'Game of Thrones' ... So, we go, we find this gorgeous park, and he presents me with this book that he said he's been working on for a while. And he's like, it's our story ... we're going to forget things along the way, so we need to constantly fill this out, so our kids can know our story.

"And when I got to the end there was like a little part I peeled open and it was my ring was inside. It was so sweet.. He got down on one knee and he's like, 'I forgot everything I'm supposed to say, you're my best friend.'"