Friends set an initial goal of $5,000 to "support the family and get these beautiful girls back on their feet". But the money kept pouring in, eventually reaching $24,548.
The webpage said the extra would go to the girls' family to "set them up for the future".
Brooke and Caitlin's father Richard Todd is in a dispute with Rebecca's brother-in-law, Shane Newlove, about which trust account the money should be transferred to.
Richard, who separated from Rebecca 15 months before the crash, has custody of his daughters - now aged 7 and 6 - and gave up work to care for them after the accident.
He wants the money put into an independent trust.
But after Rebecca died, her two sisters and a cousin set up a trust called the Brooke and Caitlin Trust, with Rebecca's siblings and cousin as trustees.
Newlove wants the money to go into that trust.
"I don't understand why money that has been raised for me and my children should be under their control," Richard Todd said.
"I am the girls' father, I think it should be in an independent trust. I don't think someone else should be in control of their financial future."
He said he was concerned about the effect of the money wrangle on the girls.
"If I wanted to take my girls on a holiday, (other family members) could say no."
Newlove said he wanted the money put into the trust that his wife, Rebecca's sister, had set up.
"We want to quietly grow those funds through memorial dinners and other fundraisers," he said.
"Who better to be guardians of the girls' future than their mother's sisters?"
The Givealittle page was set up by Rebecca's work colleague and close friend Mercedes Nadas.
She was upset to discover something she had created to help the family had led to a dispute instead.
"I wanted to do something because Becs was an amazing person and it is such a loss for the world," she said.
"The girls are like mini-Becs."
Nadas set up the fundraiser after visiting the girls at Starship Hospital. "All I did was set it up so people could donate. I was friends with Becs and I want this for the girls."
The Givealittle site has raised $5 million for 7,000 groups and individuals since it started five years ago.
Natalie Whitaker, of Givealittle, said the charity would review its terms to see if it could improve its legal disclosures or systems to avoid disputes like this one.
"The Givealittle member who set up the fundraiser for Caitlin and Brooke has been patiently holding the funds in a very awkward situation, awaiting clear instruction from the family regarding a formal trust for the two girls," Whitaker said.
The crash that killed Rebecca Todd was caused by Muriwai man Blair Alick McMillan, who was driving with double the legal blood-alcohol limit.
He is to be sentenced at the Waitakere District Court in November.
