Charities have criticised the government for cutting the amount of funding families in England can access to pay for therapy for adopted children by 40%.
Adoption UK said the news was "distressing" for families, who had already faced "an agonising wait" to find out whether the adoption and special guardian support fund would continue.
Last year each eligible child could access £2,500 for specialist assessment and £5,000 for therapy. But the therapy limit has now been cut to £3,000 per year, while separate funding for specialist assessment has been axed.
The government said the move would "ensure the fund is financially sustainable to allow more vulnerable children to access targeted support".
In an email to stakeholders, seen by the BBC, the Department for Education said the "difficult decision" came as demand for the fund "continues to grow significantly".
Nearly 20,000 children received support through the scheme last year, up from around 13,000 in 2019/20.
The future of the fund had been in doubt, until the government confirmed at the last minute that it would continue in 2025/26.
In response to an urgent question in the House of Commons on 1 April - the day after the fund expired - Children and Families Minister Janet Daby said £50m had been allocated for this year.
The overall funding for the scheme remains the same as last year.
However, Adoption UK said the cut in the amount available per child would have "a direct impact on children and young people who have had a very tough start in life".
The charity's chief executive, Emily Frith, said the decision was "very short-sighted at a time when there are more adoptive families in crisis than ever before".
Louisa - not her real name - has used the fund to provide therapy for her two adopted sons and said it "changed our lives".
"Without it, we fear for their future, their ability to function in the world, attend school, be safe to others and themselves, and for our family stability," she told the BBC.
Louisa said her own family and others affected were "anxious, fearful, sad and in disbelief at what [the cut] means for their children".
For the last two years, her eldest has used the maximum allocation of funding for therapy.
He had already been forced to stop his therapy sessions at the end of January because future funding had not been confirmed, leaving the family in "limbo" and "watching the decline in front of our eyes".
Louisa said this meant he had not been able to attend school full-time and she feared he would continue to go backwards if he could no longer get the same level of support.
She is also concerned that after her youngest has a specialist assessment, there will be little funding left for therapy.
Liberal Democrat spokesperson for education, children and families Munira Wilson has written to Education Secretary Bridget Phillipson calling on her to reverse the cuts.
Wilson said she was "extremely disappointed" the government had "slipped out" the announcement over the Easter break.
In her letter, she said the cuts were causing "immense worry and stress" for families and "cannot be justified".
The charity Kinship, which represents friends and families who step in to raise a child when parents are not able to, said the news was a "further blow", after therapy had been disrupted by the delay in renewing the scheme.
Chief executive Dr Lucy Peake said the government's "confused and ill-considered approach" of boosting awareness of the scheme but not supporting this with extra funding "risks pushing more families to breaking point".
Charities said the announcement would mean further delays for families trying to access therapy, while adoption agencies made adjustments to funding applications.
The fund is available for adopted children and young people up to the age of 21, as well as those aged up to 25 if they have an education, health and care plan.