The remains of Rina Yasutake, 49, were allegedly found lying on a mattress at the family's home in Helmsley, in North Yorkshire..
An earlier hearing heard police officers made the discovery after a tip off from local pharmacy staff, who said Rina's siblings "smelled of dead bodies".
Yoshika Yasutake, 53, and Takahiro Yasutake, 47, appeared at York Crown Court on December 2 alongside their mother, 76-year-old Michiko Yasutake.
Brother and sister - Yoshika and Takahiro - are accused of buying large quantities of surgical spirit from a pharmacy before the report was made on September 25 last year.
All three are charged with preventing the lawful and decent burial of a dead body without lawful excuse.
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None of the defendants have yet entered a plea and will appear next appear in the dock for a preliminary hearing on March 30.
The court heard medical and cultural reports will be prepared in advance of that date.
His Honour Judge Sean Morris, presiding over the 20 minute hearing, said: "Keep in touch with your legal teams. It's a condition of your bail that you must reside at your address, just so we know how to contact you.
"You must surrender any travel documents to the police within seven days. It's a condition that you do not leave the country. On that understanding you may leave."
All three defendants were released on bail until their next appearance on March 30.
The trial in June is expected to last two weeks.