Sale deed & Will

My friend entered into an agreement of sale paying considerable amount. The property was registered in the name of anand and his daughter in 2001 . the daughter was minor at the time of registration the said anand owing to his ill health had executed an unregistered WILL wherein he bequeathed the said property to his daughter while mentioning the other property to his son. He appointed his younger brother as guardian and executor. Later after six months he died. Now that the daughter having become Major wants to sell the property and we were assured that the property belongs to only the daughter of the deceased and were given all the Xerox copies for us to pursue the loan. E.c. was obtained. And bank loan was proceesed. Just before the registration day when bank people wants to verify the Will the vendor could not produce the Original will and stated that will is with the Guardian executor ( Paternal uncle). But the said person is denying to hand over the original will and also denying to sign as the witness in the sale deed. I was advised to add the other two legal heirs ( mother and brother ) and the guardian ( paternal uncle ) as consenting witness. Is it right ro do so. And also advise me if the so called Guardian Executor does not hand over the original WILL and also avoid to be present as witness to the document what shall we do. What could be his intention behind this. Is there any risk if we go for a sale deed without his presence.