A family court judge has refused to approve social workers' plans to separate five children whose parents have a history of drug abuse and can no longer care for them.
Judge Clifford Bellamy said he wanted a child psychologist to assess the effect of separation on the children.
He said care cases involving large sibling groups presented "significant challenges" to council social services bosses and to family court judges.
Detail of the case has emerged in a ruling published by Judge Bellamy following a private family court hearing in Derby.
Derbyshire County Council had asked for decisions to be made about the long-term futures of the children, four boys and a girl.
The judge said none of the children, who are aged between 11 and six months, could be identified.
He said social workers proposed to place the oldest child, an 11-year-old boy, into long-term foster care and place the other four children for adoption.
Social workers also planned to stop the younger four children from seeing their older brother, but said contact should be limited to an annual letter.
They said the oldest boy had an "ongoing relationship" with his mother and grandmother and feared that allowing him to see his brothers and sister might compromise the "confidentiality" of adoptive homes.
The judge was also told that the four younger children would probably have to be split up when placed for adoption because it was hard to find people willing to adopt large sibling groups.
"I am not able to approve any of the final care plans for these children at this moment," said Judge Bellamy.
"There needs to be an expert assessment of the children by an appropriately-experienced child psychologist."
The judge said he wanted the "likely impact" of separation to be assessed.
He said: "Cases involving large sibling groups present significant challenges to local authorities in terms of care planning. They also present a significant challenge to the court."
Judge Bellamy said the children's parents had a "long-standing history of drug abuse", including abuse of crack cocaine and cannabis.
The judge said their ability to provide appropriate care had been "compromised".
He said the four oldest children had been taken from the care of their parents more than a year ago and placed with a temporary carer.
The youngest boy had been taken from his mother's care at birth and placed in temporary foster care.