The fund was set up on behalf of the Los Angeles-based Zajfen family after the death of nine-year-old George Zajfen.
His mum, Kelly McKee Zajfen, announced the sudden death of her son last week.
Taking to Instagram, she wrote that she will keep going for the sake of George’s “beautiful twin sister”.
Kelly is a former model and co-founder of Alliance of Moms, an LA “community of philanthropists who support pregnant and parenting teens in LA’s foster care system”.
Meghan Markle and Prince Harry
PA Features Archive
Archie and Lilibet's was among the largest donations
GoFundMe
Her connection with the Duke and Duchess of Sussex is unclear – but screenshots from the GoFundMe page show a $5,000 donation in Archie and Lilibet's name.
That said, Meghan's ex-husband Trevor Engelson has made an £829 donation to the grieving family with wife Tracey Kurland.
Kelly, 42, wrote: "My sweet baby boy. My world is shattered into a million pieces. I have little ability to breathe. Walk. Function. Sit. Stand.
"You were the light of my life. Your smile made the room so bright and your heart was the most perfect and sweetest.
"You left this Earth and left behind so many people who loved you. I don't know how I'm able to go on. How I can function.
"How I can be the light and have joy ever again but I'm going to try."
She did not reveal the cause of her son's death.
It comes after reports emerged that Meghan and Harry have had two intruder alerts at their Montecito mansion since the start of May.
Santa Barbara Police records show officers were deployed to the house amid reports of trespassers on May 19 at around 5.44pm.
Last week, Harry won a bid to bring a High Court claim against the Home Office over his security arrangements while in the UK.
The Duke of Sussex is taking legal action over a decision not to allow him to pay for police protection for himself and his family when visiting from North America.
In the first stage of the case earlier this month, the Duke’s lawyers asked Mr Justice Swift to grant permission for a full hearing to have a judge review the Home Office’s decision.
On Friday, the High Court judge said the case could proceed, granting permission for part of Harry’s claim to have a judicial review.