Fears were expressed yesterday that funds raised for Shum Ho-yin - already more than $900,000 - could fall into the wrong hands if not carefully administered.
A children's rights activist urged the government to issue a care and protection order for the boy, amid reports that at least one of his relatives was a gambler.
The call, from Billy Wong Wai-yuk, executive secretary of the Hong Kong Committee on Children's Rights, followed yesterday's arrests over the August 25 attack.
She said social workers should oversee the use of the donations.
'It is understood that at least one of his family members is a gambler and it's likely that he is in debt,' Ms Wong said. 'I don't want Ho-yin to fall prey to any people who want money from his family.'
The boy has lived with his grandmother since his parents separated. His father has admitted having a gambling habit, but has denied being in debt to loansharks.
The Hong Kong Society for the Aged and Commercial Radio have raised more than $500,000 for Ho-yin, while the Oriental Daily has raised about $400,000. Another fund-raiser, the Apple Daily, said figures were not yet available.
The Hong Kong Society for the Aged has set up a monitoring committee to ensure Ho-yin will be the sole benefactor but the two newspapers have no such plans yet.
Ms Wong said relations within the boy's family were complicated and that another legal guardian might have to be found for Ho-yin.
'It seems his grandmother is his only shelter, but she is already 68. The government needs to step in to make sure he has someone to provide for his welfare, offer him guidance and support.'
The Social Welfare Department said it had already begun discussing Ho-yin's welfare, including custody and arrangements for the donated money, with his family.
In general, the department would have to appoint a legal guardian for a child whose parents could not take care of him, she said.
The legal guardian could be a family member or social workers under the department.