Father Visitor Visa

[sunnyhuni]

Dear All

I am british citizen and wish to bring my parents and brother to the UK from Pakistan
what visa do they need?
what documents they need to provide from pakistan?

Also I am going to get married next month, My partner came to UK on Fiance visa and I wish my parents and brother join me in my wedding,

what should I mention in my sponsorship letter?

Please if anyone could advise, or if anyone experience such situation can share their thoughts,
any help will be much appreciated.

Many thanks