Snitchsneeker user, EmmaRiddle, recently met Natalia Tena, the actress who plays Tonks at Collectormania 13 in Milton Keynes, England, and was able to discuss Tonk's role in the next two movies.

Tena has only filmed one scene for Half-Blood Prince, but it's not actually in the book.

She was only on set for the part where Death Eaters attack the Burrow at Christmas (where Harry & the Weasleys are present). She said that none of the angst of her character is there - indeed, she and Lupin are just suddenly a couple when they meet there.

Also, she doesn't want a big wedding scene, but thinks it would be fun "to have to ride a broom with a pregnant belly."
View the whole post here.