'We are all so proud of Michael for having a penis shaped like a dog!' Kate Beckinsale shares hilarious snap of her ex Sheen with Sarah Silverman and daughter Lily

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It is at first glance, a sweet portrait of a blended family, with actor Michael Sheen sitting alongside his girlfriend Sarah Silverman, ex-partner Kate Beckinsale and their daughter Lily. 

But British actress Kate showed her wicked sense of humour on Friday by making fun of the rather shadowy pet perched on Michael's lap.

'We are all so proud of Michael for having a penis shaped almost exactly like a dog,' she wrote alongside the shot.   

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Hilarious: Kate Beckinsale shared a family portrait with her daughter Lily on her Instagram while pointing out the shadow on ex-beau Michael Sheen's lap 

Pride and joy! Kate showed how well she and her blended family get along together 

Alongside the hilarious caption, the shot featured the quartet looking especially close with Kate's arm resting on Sarah's shoulder. 

Kate's eight year relationship with Michael, 47, came to an end in 2003, but co-parenting their 17-year-old daughter Lily has helped the former couple remain good friends.

The actress has since developed a firm friendship with Sarah, who started dating Michael in January 2014.

Reflecting on the close bond she shares with her former partner's new girlfriend, she recently told Stylist magazine: 'I don't know why everyone was so surprised. Sarah's such a fantastic woman, I love her and Michael and I have gotten on for years now. I've known him since I was 22, we're basically family.  

Three's certainly not a crowd! Kate says she's 'basically family' with her ex Michael and his girlfriend Sarah, who she invited to the premiere of her new movie Love and Friendship in May

'The thing that surprised me was what a big deal everybody made about us all getting on and then thinking, "F**k, that's really sad if it's that unusual.'

Kate, who divorced director husband Len Wiseman after 12-years of marriage earlier this year, also revealed that comedienne Sarah is a great influence on daughter Lily. 

She added: 'I'm completely open to any other strong, cool sensitive independent-thinking women who are going to be an influence in my daughter's life.' 

Back in the day: Kate was in a relationship with Michael from 1995 until 2003

Michael has also admitted his relationship with Sarah helped strengthen his friendship with Kate.

Speaking to Chelsea Handler on her Netflix talk show Chelsea, he explained: 'Our relationship now is probably better than it ever was. And it helps that she [Kate] actually likes Sarah more than she likes me.' 

He added: 'The only way it doesn't work out is that now I have not only Sarah, but also Kate and my daughter Lily, who all just make fun of me and embarrass me at any given point.' 

Proud mum: Kate is mother to 17-year old daughter Lily with ex-partner Michael