esa appeal

Hi new to this so hope you can help

Father in law just notified that after 365 days being reduced benefit as on WRAG .
Appealed as although initially on ESA because of mobility ,he has had serious mental-depressive issues(which were diagnosed in initial ESA medical).
Applied as his representative that he should be on the support group ESA because of his personal action ie severe mood disorder ,inability to cope with change and difficulty to relate to others,etc -i also supplied letters from both his doctor and counsellor,both supporting this view.
Just been informed that turned down as "i disagree with both the healthcare professional and the original decision makers choice of descriptors" , Advised that the tribunal service will be in touch shortly.

2 Questions

1 Can i attend tribunal as father in laws representative without him present as he is terrified almost panic stricken about attending - however it is awful that he has been turned down and his wife and family feel it would be wrong not to fight this.
2 Even though original ESA claim and medical report stated his depression (which is now much worse) the report says he is on ESA primarily because of knee condition-how will this affect tribunal hearing?

Thanks Gordon ,original ESA50 states amongst other things "mobility issues,plus insecurity feelings mean i cannot even contemplate organising or planning anything ,i would be lost without my wife" and "dont like people around me ,dont feel comfortable even with friends and family .....if i am in that situation it takes me days to get over it . ...i am not comfortable with change of any sort... because of my insecurities i feel i may appear rude when because of fear i am withdrawn"
The ESA medical report states"diagnosed with depression Dec 2010,having counselling-symptoms include -feeling anxious eg going to new places ,does not feel like going out ,the majority of days are bad and have in past had thoughts of suicide "though assesment summary included the following_-"a history of depression was reported ,he sees his GP For medication and takes an antidepressant medication and is on course of counselling -today with wife present mental state was normal and no obvious signs of anxiety,he can read newspapers and use a phone and spend time with grandchildren-significant disability due to mental health function is unlikely"
In GL 24 on 18/06 we stated that in essence "shirley(his wife) is almost his full time carer due to his mood disorders inability to cope with change or get to places or relate to others .
This has been turned down.

I appreciate the fact my FIL should if possible attend ,if he cannot ,i am more than capable of speaking on his behalf or providing a written submisssion if this proves worthwhile , both his GP and Counsellor support our case .

The benefit people ,have phoned on two occasions to his wife ,suggesting appeal is withdrawn and pension credit applied for!!!

Have arranged appointment at CAB -can they apply for pension credit while appealing? With regard to appeal had tribunal letter today for appeal -FIL now terrified and asking his Drs advice on whether in his opinion if he should attend and if not could he write a letter stating this . Still undecided whether to give written statement instead of attending appeal without FIl ,though MIL ,who is basically his carer wants to go along and is prepared to give evidence !! If we went down the written statement route and lost again ,is that it or can you then go upper tribunal?