Sister wants to come to UK for high school

I qualify for ILR in a few months. (via 5 years on Tier 2)

My 16-year old sister that wants to enter a sixth form college in the UK. (She is an American citizen.)

Would she be able to apply to enter as a dependent of me, or would she have to apply for her own student visa?

She'll need a child student visa (Tier 4 child). Only partners, children and adult dependent relatives are considered as dependents. She'll need to meet the maintenance requirements.

Note tier 4 child students can only study at private schools.

Thanks for the responses.

Would we have to get enrollment and invitation from the school first?

MrBrilliant wrote:
Would we have to get enrollment and invitation from the school first?

Yes, you'll need to submit a confirmation of acceptance of studies - it's a reference number which the school gives you.