Kevin and Christine Williams collected £22,500 to pay for pioneering stem cell treatment for their seven-year-old daughter Abigail. After being told that further treatment would not work they decided to donate the fund to help three-year-old Kyle Weaver walk for the first time.
For more news from north Wales click here.
Mr Williams said: "She's just not well enough - unfortunately the last 12 months Abigail has got a lot more poorly. We still owe a large debt of gratitude to the public for what they did for Abigail.
"It's Kyle's money now - his needs are more imminent than Abigail's. Hopefully people who donated will understand."
Abigail has the rare Batten's disease which affects her mobility and senses.
Kyle's parents Simon and Samantha Weaver, live 10 miles away in Llysfaen, North Wales. They said they were "stunned" by the generous donation.
More top news
Eight members of a multi-million pounds drug gang operating out of Cardiff have been jailed for a combined total of 54 years.
Ex-convict could have been suffering from drug-induced "excited delirium" when he attacked and killed a young woman, an inquest has heard.
New figures show that council tax in Wales remains lower than in England.