The basis of the prosecution of all three adults living in the house was set out in the opening speech:
"[...] prosecutors say it is “inconceivable that one of the adults alone, or two of them, could have carried out what amounts to a campaign of abuse without the complicity, participation, assistance and encouragement of the others”.
[...]
“None of the defendants did anything to prevent what was happening to Sara, as they surely would have done if they had not been complicit in what was happening. The prosecution case is that they are all responsible for her death, and they are all guilty of her murder.”
www.standard.co.uk
The article states that Malik says he was unaware of the abuse and assaults of Sara. To me, that denial demonstrates he had the power and the personal responsibility to intervene and stop it if he was aware. The extremity of the abuse and Sara's condition and her constant pain must have been apparent to everybody in the household, and so too her disappearance from the living areas of the house. She would not have been able to walk to the bathroom even.
"[...] prosecutors say it is “inconceivable that one of the adults alone, or two of them, could have carried out what amounts to a campaign of abuse without the complicity, participation, assistance and encouragement of the others”.
[...]
“None of the defendants did anything to prevent what was happening to Sara, as they surely would have done if they had not been complicit in what was happening. The prosecution case is that they are all responsible for her death, and they are all guilty of her murder.”

Sara Sharif's father 'confessed to killing 10-year-old in punishment beating'
Sara Sharif, 10, was beaten to death and left alone as her family fled to Pakistan

The article states that Malik says he was unaware of the abuse and assaults of Sara. To me, that denial demonstrates he had the power and the personal responsibility to intervene and stop it if he was aware. The extremity of the abuse and Sara's condition and her constant pain must have been apparent to everybody in the household, and so too her disappearance from the living areas of the house. She would not have been able to walk to the bathroom even.