• Testimony of aged witness in will

Dear Lawyer, My grandfather wrote will before dying to divide share of his self earned property equally between his four sons( I am daughter of 3rd son) .My grandpa also stated to give 20k each to two of his daughters.The will was prepared 12 years back.After his death, his sons did not execute will due to financial problems.Now after 12 years, when the sons showed the will to daughters and wanted to execute will, the daughters have filed a case that will was forged and that was the reason the will was not executed immediately after my grandpas death.Its been three years since case was filed and progress is slow.The 2 witness are very old.Is there a provision in court to record the aged witnesses testimony and attach it to the case file , so that even in the event of the witnesses death , it wouldn't weaken the case on sons part .please tell the procedure to request court to record witness testimony