Natalia Tena talks about her role in Half-Blood Prince was at Collectormania 13 in England and spoke with Natalia Tena, who plays Tonks in Order of the Phoenix and Half-Blood Prince. Tena revealed that she has completed filming for HBP:

The only scene Natalia has filmed for the movie, isn't actually in the book at all. 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.

Read more at Snitch Seeker. Thanks to Trish for the tip!