Paragraph ST 34.2 States - Child applicant’s parents must each be either applying at the same time as the applicant or have permission to be in the UK (other than as a visitor) unless the parent with permission as a Student is the sole surviving parent or has sole responsibility for the child’s upbringing
• Please provide Details of your parents Visa application to travel with you to the UK or proof in the form of a court document to evidence that the parent that you are travelling with has sole legal responsibility.

personal59:
Paragraph ST 34.2 States - Child applicant’s parents must each be either applying at the same time as the applicant or have permission to be in the UK (other than as a visitor) unless the parent with permission as a Student is the sole surviving parent or has sole responsibility for the child’s upbringing
• Please provide Details of your parents Visa application to travel with you to the UK or proof in the form of a court document to evidence that the parent that you are travelling with has sole legal responsibility.

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https://www.nairaland.com/6954875/uk-student-visa-tier-4