src/Controllers/ChildCrudController.php
protected function beforeSaveEntity(Request $request, \Illuminate\Database\Eloquent\Model $entity)
    {
        $relationship = $this->getRelationship($request);
        if ($relationship instanceof HasMany) {
            $this->getInverseRelationship($entity)->associate($this->getParent($request));
        }
    }
protected function beforeSaveEntity(Request $request, \Illuminate\Database\Eloquent\Model $entity)
    {
        $relationship = $this->getRelationship($request);
        if ($relationship instanceof HasMany) {
            $this->getInverseRelationship($entity)->associate($this->getParent($request));
        }
    }
Called before saveEntity
@param \Illuminate\Database\Eloquent\Model $entity