Heiress is a huge hit with former Beatle's kids
The couple started dating last November, but until now she had only met his designer daughter Stella, 36.
Nancy, 47, and Stella are said to have got on ‘like a house on fire’.
‘It was very relaxed and everyone had a great time,’ a source tells the News Of The World.
‘After [Heather Mills], Paul doesn’t want to bring anyone to meet the family unless he’s certain.’
Sir Paul, 66, gave ex wife Heather, 41, a £24.3m divorce settlement.