Food writer Ella Woodward will be inviting her father - former Northern Ireland secretary Shaun Woodward - and his new boyfriend to her spring wedding.
Ms Woodward said she was thrilled her father had found happiness with Luke Redgrave, grandson of the actor Sir Michael Redgrave.
The Deliciously Ella food blogger told ES Magazine: "Growing up, my dad was the ultimate person for open-mindedness.
"No matter how much someone was like, 'Whoa can you believe so-and-so is like that?' he'd be like, 'Well, why does it matter to you?' And that rubbed off on us."
Her parents, Mr Woodward and Camilla Sainsbury, announced their split late last year after 28 years of marriage.
She said: "Obviously it's sad that (my parents) have split up, and not one of the easiest things to deal with, but my siblings and I feel that even if the transition is difficult, everyone will end up happier."
The 24-year-old added: "Dad is happy. And to be honest that's fundamentally what matters. If this is what he wants in his life, then good for me."
She continued: "Honestly, I have been able to accept my father's new relationship because you get to that point with your parents that you realise it's their life, not yours.
"I have my life. I have Matt. I have my work, which I love, and I have my friends. So as long as my mum is okay, which she absolutely is, and my dad is okay, to be honest, it's fine."
And with a wedding planned for April, she confirmed that Redgrave would be invited: "He's definitely coming to the wedding. Absolutely."
Ms Woodward is marrying Matthew Mills, the son of former culture secretary Tessa Jowell and lawyer David Mills.
The two have planned a wedding for April, where they will serve fish, potatoes and meat - despite Ms Woodward's gluten-free cookbooks and vegetarian lifestyle.
She explained: "It wouldn't be fair on Matt to say: 'Okay, guys, we're doing a wheat-free vegetarian wedding - woohoo!'"