Forged signatures

Dear sir, my dad is holding a proprietor company since many yrs. Then he enetered into partnership before 18yrs with the person in whos godown he use to keep his stock. But later 16 yrs ago dispute arised and he could not communicate with the partner, also my dad was bankrupt, as that person blocked my dad's stock and even did not pay rs 7 lacs against the bill for which he purchased frm my dad. We had no money & time to take legal actions. My dad sent him one notice through laywer via registered id, to which he did not accept. However my dad managed to setup a fair buisness again. But nw we got to knw that in 2001(14 yrs ago), the partner forged my dad's signature on legal documents and managed to transfer this partnership company on his name as proprietor. Later in 2006(8yrs ago), he gave the asset of company (land & machineries) on lease to his son for his buisness. we do have the documents copy with us which we got through rti on 20th october 2015. kindly please suggest us into this matter.