single mutation to update relationships

update-relationships.graphql

#Without query variables

mutation updateChildren {  
  delete_children(where: {parent_id: {_eq: 1}}) {
    affected_rows
  }
  
  insert_children(objects: [{name: "child1", parent_id: 1}, {name: "child2", parent_id: 1}]) {
    affected_rows
  }
}

#######################################################

#With query variables

mutation updateChildrenWithQueryVars ($parentId: Int!, $newChildren: [insert_children_input!]!) {
  delete_children(where: {parent_id: {_eq: $parentId}}) {
    affected_rows
  }
  
  insert_children(objects: $newChildren) {
    affected_rows
  }
}