In such situations the court should be asked to provide consent to the treatment. (bevanbrittan.com)
As with adults, if a child or young person is competent / capable, they can provide valid consent to treatment / care. (bevanbrittan.com)
In the case where consent to treatment is withdrawn but the participant agrees to remain in the research study, the participant is followed to completion. (trialsjournal.biomedcentral.com)