I am afraid at present we do not have this available on our labels. You could add Parent/Guardian on the Customisable Fields of the label - then you would be able to include this statement on your labels.
Enter your text by over typing custom text and then click on save.
Then click, drag n drop onto the label editor adding additional fields as required.
Note. Remember to check the label preview located at the bottom of the screen so you can make any necessary adjustments.