Two children suffered abuse and neglect that left one with extensive burns and the other so malnourished he could barely walk.
The children, from different families in Great Yarmouth, were subject to serious case reviews by Norfolk Safeguarding Children Partnership.
In both cases questions were raised over their care by multiple agencies.
The children have since been placed into foster care and police investigations are ongoing.
The girl, aged five, set herself on fire while playing with a cigarette lighter in August 2019, two days after intervention by children's services was downgraded.
She suffered burns to 26% of her body.
Paramedics and police made multiple visits between January 2018 and August 2019 due to injuries to the child and reports of anti-social behaviour at her home, resulting in referrals to children's services.
The review found an overreliance on information being available to partner agencies through online systems.
Similar issues were identified in the case of the malnourished boy, aged two.
This and other significant health issues, including arm fractures, were found during a child protection medical in August 2018 shortly after the level of intervention with the family was downgraded.
The review raised questions about his supervision, citing: "It is difficult to understand how a child who was receiving services from a number of agencies in Norfolk was diagnosed with severe malnourishment in 2018."
The family, who identified as travellers, had been subject to multiple child safety reviews about the boy's siblings not attending school, cramped living conditions and a previous claim of domestic abuse.
The report praised the "tenacity" of a midwife who visited the family and raised concerns.
Recommendations were made in both cases for a better transfer of safeguarding records.
Chris Robson, chairman of the safeguarding partnership, said neglect cases were "particularly difficult" due to different perceptions of it and when to intervene.
"There are a range of measures taking place to further strengthen safeguarding practice and help professionals to better understand the risks and challenges facing children and families," he said.