It is your legal obligation to let data subjects know what data you hold, why you hold the data and who you share it with. Most data regarding children and parents is collected using an enrollment form.
This form should be used to gain consent not only from parents but from authorised collectors and emergency contact persons (as this information is also stored by you).
Your Enrollment (Registration Form) should collect consent from parents, emergency contacts and authorised collectors. You also need to share your privacy statement with parents/guardians which should be attached to the form. Our new pack which will be ready very soon contains an updated form with consent and privacy statement built in.