Child Settlement Visa UK

Dear All,

I am looking for some advice on behalf of some close friends. The great advice I received here when I applied for my wife's settlement visa and subsequent citizenship starting back in 2009 was invaluable.

They are a British guy married to a Thai who has had indefinite leave to remain since 2013. She has a son who currently lives in Thailand with her mother, he is 15 years old and will be 16 around next April. They would like to bring him over on a permanent basis. He came to the UK last year on a visit visa for a few months to see how he got on and is looking forward to joining his mother next year, the application is to be submitted in March. They should not have any difficulty proving sole responsibility which looks to be the most difficult hurdle.

The specific questions we have are:

Which form or forms are required to to be completed?

Is there a fast track service available - the forms will be submitted in Bangkok?

Many thanks