How to get a b2 visa extension

[ana29]

My fiances b2 10 yr multiple entry visa expires this December and we would like to know if it is still possible to get an extension. He would like to stay for a few more months because his cousin asked him to be part of her wedding that takes place in March and also because we will be getting married next month, and it would be nice for us to be closer together while the process is going on for his PR. are these good reasons to ask to stay? We have the invitation from the wedding she invited us to. Would this be good to send with the request? Do they decline a lot of peoples requests. Please share experiences!
Thanks in advance
Ana

[immihelp]

Read https://www.immihelp.com/visitors-visa-extension/