The 69-year-old musician – who got engaged to Katharine in July 2017 – can’t wait to tie the knot with the 34-year-old actress soon.
Sharing a picture of his fiancé on Instagram, he captioned it: "I won the lottery!!! (sic)"
The photograph was a repost of something Katherine had posted on her Instagram story, where she admitted she "can’t wait" to marry David.
She wrote: "Far away from each other but still can’t wait to marry you @davidfoster (sic)"
And David’s daughter Sara thinks Katherine will be a "great addition" to the family.
She said: "She’s great. She’s a great addition. You know I’ve learned to not rule anything out [like David and Katherine having children] . I think anything is possible at this point. Who knows? … She’s wonderful. The other day she was like, ‘I got you a facial,’ and like that’s so cool. My dad loves love and my dad loves commitment. My dad’s always been married. He’s never been single really. He’s a real commitment, marriage kind of guy and I’m happy for him."
And David’s daughter Amy thinks he and Katharine are "perfect for each other".
She said: "I know that some people have been hating on that relationship. All I can tell you is it absolutely works when you see them together. It’s love. The haters [can] shut the f**k up because they are perfect for each other. I’m so close with [McPhee] . She’s amazing and funny, fun, smart, elegant, timeless, beautiful, talented. I can’t say enough about her."