Two 17-year-olds, a 15-year-old and a 38-year-old man allegedly attacked the woman, 18, in the restaurant at Lugarno in southern Sydney in October last year.

Family members wept in Parramatta Children's Court on Monday as the teens were granted bail with conditions that they report daily to police, not talk to each other or the woman and only leave their homes with their parents.

The Crown alleges that the woman had consensual sex with one of the 17-year-olds in the toilet of the pizza shop on Forest Road, before he told her that "the others want to have sex with you".

She was then allegedly repeatedly sexually assaulted by the other two teens and the man, Ricardo Audish, before she was dropped off in Riverwood CBD.

Police said a passerby found her, and she was taken to Liverpool Hospital by emergency services.

A toxicology report allegedly detected cannabis in her blood stream.

The court heard that two months after the alleged rapes the older teens met the girl by chance in Parramatta.

One of the boys allegedly told her that he would do whatever it took to convince her to drop the charges. The court heard the woman flagged down a passing police car.

Intercepted telephone conversations also allegedly captured the accused discussing what they should tell police about where they got cannabis.

One of the 17-year-olds, the 15-year-old and Mr Audish were charged with aggravated sexual assault in company and deprive liberty.

The other 17-year-old was charged with being an accessory before and after the fact to the offences.

The Crown case is that the latter had an "integral role" in the attack. He allegedly organised for the woman to come to the pizza shop and was aware she did not consent to have sex with anyone but him.

Prosecutor Peter Clayton opposed bail arguing that the teens could collude with each other, try to flee the country or attempt to intimidate the woman.

Elizabeth Nicholson, a Legal Aid-appointed barrister for the older teens, said that there were several weaknesses in the Crown case, including whether or not the woman had consented to have sex with them.

Ms Nicholson said the woman had freedom of movement throughout the evening, and had made a phone call to a friend asking her to come and collect her because she had taken something and was not feeling well.

The court heard that the 17-year-olds, who have both left school, and the 15-year-old, who arrived in Australia as a refugee from Iraq last year, had no criminal history.

They live in western Sydney with their families.

Magistrate Terry Murphy said the charges against them were among the most serious, but noted that there were certain aspects of the Crown case that were weak.

"I'm of the view that strict bail conditions can protect the victim and ensure the integrity of the investigation," Mr Murphy said.

The boys were forbidden from leaving their homes without their parents; the 15-year-old was given an exception to travel to and from the school where he is learning English.

They are next due to face court on Friday, when police will make an application to obtain DNA samples from them.

Mr Audish, who is from Elizabeth Hills in western Sydney, remains behind bars and will next face court in March.