The Austens move from Bath to Castle Square, Southampton. This is where Jane tries and fails to secure "Susan" for publication in 1809. Jane's older brother, Frank, lived in Southampton with his family, so therefore it made sense for his mother and his sisters to move in with them as well. Households often stayed together during this time to conserve the family money, help out with household items, etc.

Austen, Jane. Mansfield Park, edited by June Sturrock, Broadview Press, 2003.