You can do it by yourself or ask for help.
Declaring a legal guardian
Regarding the registration of minor children, it is assumed that from the age of sixteen, minors are capable of registering consent by themselves. Before the age of sixteen, this right reverts back to the legal representative.
When a patient is mentally incapacitated and incapable of exercising his or her rights, the person’s legal representative may act on their behalf, provided information requests are done in the exclusive interest of the patient.