Visitor visa for Sister-in-law under 18

[np123]

I want to apply for my sister-in-laws visitor visa. She is under 18 right now.
UK Visa immigration site mentions that for under 18, we should apply Child Visitor visa..

https://www.gov.uk/child-visit-visa/doc ... st-provide


There is mention of below doc required
- proof you can support yourself during your trip (eg bank statements) or that you’ll be financially supported by your parents or carers

My doubt is, my father-in-law cant show much on his bank statement but I will be taking care of here stay in UK.


1. Can i show my bank stmts in UK as proof of support for her travel and stay?
2. do i need to show any proof of relation with her (such as marriage certificate, my wife's passport page)?

Also i dont see below docs mentioned in the list for child visitor
- invitation letter
- sponsorship letter
- proof that she will be returning

3. Do i need to attach any of these docs if i want to take care of expense of her stay?

if i get clarification around question 1,2 and 3, that will be helpful..
Any further inputs will be appreciated..


Thanks,