Mairead Philpott tells prosecutor Richard Latham QC that it is "possible" her husband Mick got out of bed to light the fire.
She agrees with him that there was no mention of this in her defence case statement.
Mr Latham asks why she would say nothing of this in her interview if she was innocent. Mairead says she was following advice.
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A 35-year-old and a 27-year-old man, both from the Birmingham area, have been arrested and remain in police custody.
Molly Owens, was reported missing on Friday and is believed to be with her father, who is wanted after failing to appear in court.
Former Diversity dancer Robert Anker has died in a car crash in Canada.