The Wunderlich's have been battling to home school their children and recently lost their case at the European Court of Human Rights.
Home schooling is illegal in Germany.
Petra and Dirk Wunderlich took legal action after more than 30 police officers and social workers raided their home and forcefully removed their children back in 2013.
They were later returned.
While they are continuing to fight the case, the family have been requested to return to a court in Darmstadt to ensure the children are attending school.
Criticising the continued action facing the family, Robert Clarke, Director of European Advocacy for religious freedom charity ADF International and lead counsel for the Wunderlich family, said: "The Wunderlich family has experienced significant turmoil at the hands of the German authorities.
"In the end, the children were assessed as doing well. It is hard to understand why the German authorities persist in challenging the custody of the children.
"Why would anyone be interested in removing the children from their loving family home after German courts and even the European Court of Human Rights acknowledged that 'the learning assessment had shown that the knowledge level of the children was not alarming and that the children were not being kept from school against their will.'"
Dirk Wunderlich said: "It is frustrating that we are faced with this additional challenge in Germany concerning the custody of our two youngest children.
"The children are happy and healthy and their level of education is good, as was also recognized by the European Court of Human Rights in its judgment in January.
"The persistence of the authorities in trying to remove them from our care is shocking."
The family have asked for their case to be referred to the Grand Chamber of the European Court of Human Rights and are currently waiting for a response from the highest level of the Court.
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