The elder brother of Manchester Arena suicide bomber Salman Abedi will be told he must give evidence to the public inquiry.
Ismail Abedi is refusing to co-operate with the probe, which is looking at how his two younger brothers, Salman and Hashem, became radicalised and planned their deadly bomb plot.
Images from devices recovered at Ismail Abedi's home during a police raid the day after the bombing indicated he was "sympathetic to the ideals of Isis" (so-called Islamic State), the inquiry has heard.
He was arrested, held for 14 days and interviewed by detectives 25 times, but not charged with any offence, and he denies any involvement.
Mr Abedi had initially refused to give a statement to the inquiry, claiming his legal privilege not to incriminate himself.
Paul Greaney QC, counsel to the inquiry, said Ismail, convicted terrorist Abdalraouf Abdallah and a friend of the Abedi brother's, Ahmed Taghdi, had all refused to co-operate. All three deny any knowledge of the bomb plot.
But Mr Greaney he said he now expected all three are to be served with a legal notice from the inquiry chairman, retired High Court judge Sir John Saunders.
He said the notice "will require the attendance" of all three at the inquiry to give evidence in person in October.
Mr Greaney outlined a substantial legal to-ing and fro-ing with lawyers for the three men to ask them to provide statements and give evidence.
Mr Greaney said there are "legitimate and important" questions for Ismail Abedi to answer "about the involvement of his brothers in the murders of 22 people".
The police raid on Ismail Abedi's home recovered a disk drive containing a number of images that could be "considered supportive of an extremist mindset", Detective Chief Superintendent Simon Barraclough of Greater Manchester Police (GMP) told the inquiry last year.
Mr Abedi told police he had concerns about Salman Abedi and their younger brother, Hashem, over them dropping out of their studies.
He denied any knowledge or involvement in his brother's actions or their radicalisation or assistance in relation to the attack, or that he had known or suspected a plot.
Abdallah denies "grooming" Salman Abedi, who the bomber twice visited in prison, discussing "martyrdom" with him.
He was released from jail in November on licence after serving a sentence for terror offences, before being recalled in January.
Ahmed Taghdi, Salman's friend, searched and arranged the urgent purchase of a car, a £230 Nissan Micra used to store bomb-making equipment.
He was arrested but denied any knowledge of the attack and was subsequently released without charge.
Salman Abedi, 22, detonated a home-made shrapnel-packed bomb at the end of an Ariana Grande concert at the arena on May 22 2017, killing 22 bystanders and injuring hundreds more.
His brother Hashem was jailed in 2020 for a minimum of 55 years before parole for his part in the bomb plot.
The inquiry was adjourned until Thursday morning.
Meanwhile, a survivor of the Arena attack has told how he spent 21-minutes helping the injured before armed police ordered him to leave.
Darren Buckley was at the concert with his son.
Mr Buckley told the public inquiry today that he went into the city room, where the blast happened, to offer his assistance
Martin Hibbert's statement was read out. It said he went with his daughter to the concert and was crossing the foyer when the bomb exploded.