Attendant-care payments approved by ACC gave Mrs Carpenter enough to live on as she looked after Paige while the family lived in New Zealand and later Australia.
But when personal circumstances forced her to move to England, the contract changed and the money stopped coming.
ACC reviewed the case this year and offered a package of attendant and sleep-over care, and in the meantime approved care under an "extended discretion" period to allow time to collect medical information from the UK.
In the latest turn, ACC told Mrs Carpenter that as she was no longer being paid as a caregiver for Paige through contracted agency Geneva - and because Geneva was unable to employ carers who lived overseas - the rate had changed again.
The family say the payments had now fallen to a third of what they were, which Mrs Carpenter said had proved "devastating".
ACC has told the family their previous rate would be reinstated should they return to New Zealand, but the Lamings say they have no support network for Paige here.
Their current contract forced them to return to New Zealand several times this year to qualify for payments.
Lawyers had challenged the decision in court, arguing there was "no logical reason" Paige could not receive the same payment in Britain, but the case was dismissed.
Wellington firm John Miller Law, representing the family, launched further tribunal action.
Practice manager Jonathon Miller said the case was a result of Parliament establishing that payment for overseas claimants was available only through attendant care, with decisions at the discretion of ACC and not challengeable.
"No one denies that if Paige was back here in New Zealand, she'd be getting attendant care - but it's just really the stopping of the payments, and whether we can legally challenge that," he said.
"It's not a matter of how horrible the ACC decision seems, or how unjustified it is - the bottom line is there's a provision in the act which says you're not allowed to challenge these types of decisions."
Mr Little said he had not seen anything like the case. "From what I've seen, I can't understand why ACC has made the payments, stopped the payments, and then put them through the extra hassle of demonstrating their situation," he said.
"I just think there's got to be a better and more streamlined way for ACC to handle their particular case. There just seems to be a lack of transparency about it at the very least, and that needs to be clarified."
Citing privacy reasons, ACC said it could not comment on the case.
Mrs Carpenter said she would campaign for legislation to be changed so people damaged as a result of a health professional's actions could be supported wherever they chose to live.
