Authorities say Joshua Dale Brown, 26, worked at 23 facilities since 2017 and have recommended an additional 800 children who crossed paths with him be tested for infectious diseases.
Childcare giant G8 Education said he also worked one shift at World of Learning Point Cook, bringing the total number of centres to 24.
The allegations have put childcare record-keeping in the spotlight, with police forced to use search warrants to confirm Brown's employment history.
The mother of a child at one of the newly-added sites at Mickleham, in Melbourne's north, said parents were stressed and upset on Tuesday when they were informed Brown worked there in August 2024.
"I was pretty worried and concerned about my child's safety," the mother, who wished to remain anonymous, told AAP.
Her child wasn't enrolled when Brown was employed for one shift, but she was still upset at the daily drop-off.
"Our hands are tied, we're relying on the childcare at this stage but I wish I didn't have to send my child," the mother said.
"No matter how many precautions you take, there could be some sort of things going on that you wouldn't know about.
"But I think the cameras and CCTV, they could be really important."
Brown is charged with more than 70 sex offences against eight children younger than two at the G8-owned Creative Garden centre at Point Cook, in Melbourne's southwest, between April 2022 and January 2023.
It has been revealed he had worked at four more Affinity Education childcare centres than first listed, worked at Papilio Early Learning in Essendon for an extra six months and did not work at the chain's Hoppers Crossing centre.
Investigators blamed the two-week delay in releasing his complete work history on childcare record-keeping practices.
"This has been extremely complex due to childcare approved providers not having centralised records, requiring detectives to execute search warrants to obtain handwritten records, shift rosters and other critical information," a police spokesperson said.Â
An Affinity Education spokeswoman said the company had reviewed employment and staffing records since being briefed on the matter on July 1 and had provided information to police.
Federal Education Minister Jason Clare said the "nightmare" case highlighted the need for a national register of childcare workers, which would help authorities identify red flags when workers were moving for the wrong reasons.
He noted some employees move between centres as labour-hire workers but others may cross over because they're "quietly being moved on".
"If the system works the way it needs to, when something is not right, the police are called, the regulator comes in and, if necessary, the centre is shut down," Mr Clare told reporters in Sydney.
Early education advocate and consultant Lisa Bryant said it was incredible major childcare providers didn't have a centralised record-keeping system to track the exact dates when staff were working.
"This is very unusual. If any other childcare centre could not give accurate employment records, it would be a major problem," she told AAP.
Ms Bryant said there was a high degree of software use in the sector, including to record children's attendance, communicate with parents and record when educators were on duty to prove to regulators they were meeting ratios.
Melody Glaister, whose daughter attended a centre while Brown worked there, said it was ridiculous there was no centralised system.
Victorian Skills Minister Gayle Tierney said a state register of workers was expected to be completed in eight weeks.
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National Sexual Abuse and Redress Support Service 1800 211 028
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