Chia Liang Saw appeared in Perth Magistrates Court on Friday to face 53 charges, including sexually penetrating a child.
During a part-heard bail application, adjourned so a home detention report could be completed, the court was told the 41-year-old doctor would be charged with a further five offences in the coming days.
The court was told Saw was facing 20 charges of intent to procure a person under 16 years to engage in sexual activity based on alleged communications with a woman variously described in court as a "vigilante" and "pedophile hunter".
The woman, who is not a police officer, used a social media app and presented herself as a child and engaged in conversations, with the court previously told it was the Sugar Daddy website.
The woman then passed the information to investigators.
Saw was charged in late May with persistent sexual conduct with a child under 16 and possessing child exploitation material.
He was slugged with another 31 charges in mid-June, including seven counts each of indecent dealing with a child under 13 years and producing child exploitation material.
A further 20 new charges were brought on Tuesday related to the communications with the third party.
Saw's alleged victims included patients, eight of them girls aged 12 to 15, a 10-year-old girl allegedly abused at his family home, and a 13-year-old girl allegedly exploited online.
The doctor, whose medical registration has been suspended, allegedly sexually abused and recorded child patients he was treating for ADHD.
The court was also told further details about a series of "concerning" emails Saw allegedly sent to three children.
In one, Saw allegedly offered to buy the child a ukulele. In another, Saw allegedly said he spotted the child outside their school before wishing them a good weekend.
Saw also allegedly created an email account for a child patient so he could communicate with the child.
"A pediatrician contacting a child patient directly is startling in the broader context of these charges," Magistrate Matthew Walton said.
"If convicted, Mr Saw would receive an immediate term of imprisonment of substantial length."
Some of the emails were sent to one of the children while the child was in class and the child was responding, the court was told.
During discussions over the conduct, Saw's lawyer Alex Smith conceded it had crossed the line professionally and that the alleged offences were "ugly and distasteful".
He also said Saw had communicated with one patient turned complainant because she was "extremely troubled" and the pediatrician was attempting to establish rapport.
Mr Smith previously said Saw denied the persistent sexual conduct allegations and the recordings were made by the doctor to protect himself against allegations.
Saw was not required to enter a plea and was remanded in custody to reappear in the same court on July 10, when his bail application will continue.
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