Milo Ventimiglia attended the college graduation of his on-screen son Niles Fitch in 'This Is Us'

Hannah took to her Instagram Story to share a photograph of Milo and herself with Niles at the graduation and simply said "congratulations".

The only person missing was their on-screen mom, Rebecca Pearson, played by Mandy Moore.

However, the 40-year-old star sent her congratulations on Instagram, and gushed that she is a "proud fake mom".

Underneath his snap in his cap and gown, she commented: "Go Niles! Unbelievable. #proudfakemom. Dad, I did it."

The entire cast of the heartwarming programme - which ran from 2016 to 2022 - were extremely close, and Mandy previously admitted she will "never, ever" have a working relationship like the one she had with Milo again.

She told Variety: "It was effortless from the beginning, and it was effortless through the end. I acknowledge that I will never, ever have an on-screen partner like Milo again. It's so rare to connect with someone on that level. In every way, this job was once in a lifetime."

During their final scenes in the show, Milo smuggled tissues onto set to blot his co-star's tears, and the pair had to use breaks in filming to move props around to hide the signs of Mandy's emotion.

She said: "Sweet Milo had a tissue ball underneath the pillow for me.

"Each take, Milo would very gingerly help me flip the pillow over, so you didn't see the tear stains. We were just trying to configure the pillow every take to make sure you couldn't see where Mandy had been crying!

"He'd hand me my little wad of tissues to sop up the tears. It was so indicative of our relationship and the way we always supported each other and had each other's back. "

The Emmy-winning series followed two families in different timeframes.

Chrissy Metz, 43, who played grownup Kate alongside Justin Hartley, 47, as brother Kevin Pearson - the biological son of Jack and Rebecca - admitted last year she still misses being on the show.

She told People: "I miss 'This Is Us' desperately. And not only was it life-changing for me, but the best people, the way that it touched people's lives and hearts and minds, it was really, really special."