The charred stays of Sophie Lionnet, 21, were found in the garden of a residence in Southfields, south west London, on 20 Sep last year.
Police were primarily incompetent to brand the physique due to its condition.
They after reliable it was Ms Lionnet, of Wandsworth, who was creatively from Troyes in north easterly France.
Designer Sabrina Kouider, 34, and her partner Ouissem Medouni, 40, of Wandsworth, repudiate murdering the nanny on or before 20 September.
They certified at the Old Bailey on Friday to a second charge of perverting the march of probity by attempting to “dispose of the physique of Sophie Lionnet by burning”.
Kouider, wearing a white shirt and black blazer, seemed weeping as she sat in the dock.
A French interpreter helped her follow the hearing.
Medouni, wearing a burgundy jumper, paused for a moment before entering a guilty defence to perverting the march of justice.
The couple face a five-week hearing starting on 19 March.