Robert Shepherd and his sister Christianne died in October 2006
Two Thomas Cook employees have gone on trial in Greece accused of the manslaughter of two children on the island of Corfu.
Nicola Gibson and Richard Carson are on trial along with 10 Greek nationals, after the deaths of Robert Shepherd, six, and his sister Christianne.
Robert and Christianne, seven, died in October 2006 from carbon monoxide poisoning at a holiday apartment.
The defendants are all charged with manslaughter by negligence.
The children's father Neil, 38, of Horbury, West Yorkshire, and partner Ruth Beatson, 28, were also in the apartment but survived the incident.
Nicola Gibson and Richard Carson are on trial along with 10 Greek nationals
During the trial, the jury will hear evidence on whether Ms Gibson, 25, and Mr Carson, 27, carried out the correct safety assessments at the apartment.
The family were on half term holiday when the incident happened at the Louis Corcyra Beach Hotel where they were staying.
A chambermaid found the children's bodies.
The couple only became aware the children had died in the bungalow when they came round from treatment for the effects of carbon monoxide poisoning.
Mr Shepherd and Ms Beatson arrived at court with the children's mother, Sharon Wood and her husband Paul.
In the year following their deaths a memorial garden was opened in memory of the brother and sister, who were known as Bobby and Christi, at Horbury Primary School, in Horbury, near Wakefield, as a tribute to the former pupils.
Head teacher John Wright said: "The garden is a beautiful tribute to two children who added so much to the school and are remembered fondly by their friends and school employees."