Execution of Unregistered Grand Father 's Will

My Husband Grand Father has 3 sons and he has already shared the property between 3 sons when thy got divided from the joint family. House of Grand father has been written to his only Grand son(my husband) in his WILL . To make that effective Grand Father has asked his grand son to given 10 lakhs to youngest son, 5 lakhs to middle son and 5 lakhs to elder son(My husband is son of elder son of Grand father). Grand father has not registered the will when he wrote it. Now my husband's middle uncle is creating a problem. They are not ready to sign on NOC. Also since its time taking process to get it registered on my husband name, one of the lawyer and Will writer suggested to do a gift deed to wife so that it can be immediately transferred and we followed that procedure and property got transferred on my name . We have taken this decision since we live in USA due to our jobs. Now only the middle uncle is creating a problem and threatening us that they will go to court. They are not ready to take the cheque of 5 lakhs and and sign NOC. Please suggest what should be our next steps and how to handle this situation with court and without court.