While Pattinson's parents, Richard and Clare Pattinson, "would really like a church wedding," twigs "wants something quite informal, like a pub wedding," a source close to the Twilight star, 28, tells PEOPLE.
Fortunately, there are other nuptials coming up in the family – Pattinson's older sister Victoria also got engaged a few months ago, to her boyfriend, John Peppitt, the source says.
Pattinson and twigs, 27, are hoping to get married late this summer, though plans are "not definite," adds the source.
Sources confirmed the British stars' engagement to PEOPLE on April 1. Pattinson, who split with his Twilight costar Kristen Stewart in 2013, seems "much more calm and happy" around twigs, says another source. (Born Tahliah Barnett, twigs adopted a childhood nickname for her stage name.) The couple have been dating for six months, and they exchanged promise rings earlier this year.