Becky, 16, was reported missing on 19 February. Body parts were found at a house in the Barton Hill area of Bristol on 2 March.
Nathan Matthews, 28, from Warmley, appeared by video link at Bristol Crown Court charged with her murder.
Mr Matthews, who has yet to enter a plea to the allegation, was told a provisional trial date had been set for October.
His girlfriend, Shauna Hoare, 21, who is charged with perverting the course of justice, also appeared by video link.
Four other defendants have been charged with assisting an offender.
Jaydene Parsons, 23, appeared via video link, while James Ireland, also 23, appeared in person.
Karl and Donovan Demetrius, both 29, did not appear.
The stepbrother of teenager Becky Watts is set to stand trial for her murder.