Rufus Wainwright is to wed his long-term partner Jorn Weisbrodt on Thursday.
The 39-year-old singer and the German-born theatre producer - who got engaged in November 2010 - are to tie the knot at the home of his singer/songwriter father Loudon Wainwright III and late mother Kate McGarrigle in Montauk, New York, after same-sex marriage was made legal in the state in July 2011.
Sources told the New York Post newspaper that Yoko Ono and Carrie Fisher - who is best known for playing Princess Leia in the original 'Star Wars' trilogy in the late 70s and early 80s - are both due to attend the 'Hallelujah' singer's nuptials, along with around 250 guests.
Attendees will be treated to a lunch of champagne and lobster rolls at a local restaurant before heading to Montauk's Shagwong Restaurant - which Rufus once described as being "filthy and smelly and, once again, sexy" - for a reception which is expected to go on until 4am.
Wainwright is set to sing at the party along with a number of other live performers instead of a DJ.
The couple raise 18-month-old daughter Viva Katherine Wainwright Cohen - who Wainwright had with Lorca Cohen, the daughter of Leonard Cohen - along with the youngster's mother.
Wainwright - who has been dating Jorn for more than five years - proposed at a restaurant in London in November 2010 while the pair were enjoying an Indian meal.