Burden of proof in civil case

Sir/madam,

        I am for plaintiff side and the plaintiff filed a civil suit for effecting partition as  this plaintiff entitled for 1/8 part share in the property which belongs to her father and as her father not write any will and there are 3 male and 5 female heirs having share in this property including the plaintiff. Now the case is filed against the three brothers of the plaintiff to effect the partition.In the written statement,the defendant  No. 1 stated that he and defendant no.3 get release deed from the 4 sisters and from defendant No.2 and he states that after one year the plaintiff also give a registered release deed in favour of Defendants 1 and 3 and the defendant No.3 having half share, he sold to some other parties and now the balance half share in the property is with defendant No.1 and this plaintiff not effect any release deed and it may be created by bogus and the question is whether the burden of proof of the release deed document  relates to plaintiff or defendant .Now the case is posted for trail and another question as the plaintiff aged more than 78 years lady can we ask for commission to be appointed for filing proof affidavit in the home of the plaintiff and in which order and rule of C.P.C it to be filed and what are the procedures as the defendant to file counter for that petition and then enquiry to allow the petition all goes.kindly give me your valuable sugestions.