(defun split-components/children (data)
  (flet ((children-form-p (form)
           (and (listp form)
                (typep (car form) '(and (not null) (or list string))))))
    (let ((index (or (position-if #'children-form-p data)
                     (length data))))
      (values (subseq data 0 index)
              (subseq data index)))))