How to prove, the evidence can be witness testimony, audio and video materials, written evidence, expert conclusions, physical evidence and many other kinds. A will that is caused by external factors and does not belong to my true intention is a will made under duress or deception.
 1、 Is there a time limit for testamentary succession. But you can claim inheritance as long as the inheritance remains. If there is a dispute, there is a time limit for the lawsuit of inheritance dispute.
 1. The limitation period for cases of inheritance starts and ends two years from the date when the obligee knows that his or her rights have been violated, and the maximum limitation period does not exceed 20 years from the date when the inheritance starts.
 2. The suspension of the limitation of action refers to the suspension of the limitation of action due to certain facts (such as war, large-scale natural disasters, and the estate administrator has not yet been determined). From the date when the cause of suspension is eliminated, the limitation period continues to be calculated together with the period before the suspension. However, the legal reasons for the suspension of the limitation of action must occur in the last six months of the limitation of action, such as the suspension that did not occur before the expiration of the limitation of action. According to the provisions of the Opinions on Several Issues Concerning the Implementation of the Inheritance Law of the People's Republic of China issued by the Supreme People's Court on September 11, 1985, if the heir is unable to claim the right of succession due to irresistible reasons during the limitation period, the people's court may suspend the limitation period. Within two years from the date when the heir knows that his or her rights have been infringed, if the dispute over his or her right to inheritance is really mediated by the people's mediation committee, he or she may handle it according to the suspension of the limitation of action.
 3. When the successor brings a lawsuit to the people's court due to a dispute over inheritance, the limitation of action is interrupted.
 2、 How to Determine the Validity of Wills
 1. Inappropriate proxy, recording or oral will of the witness is invalid. According to Article 18 of the Inheritance Law, the following persons cannot be witnesses of the will: persons without capacity, persons with limited capacity; Successors and legatees; A person who has an interest in a successor or legatee. Article 36 of the Opinions stipulates that the creditors and debtors of the heirs and legatees, as well as the partners of the joint operation, shall also be regarded as having an interest with the heirs and legatees, and shall not be the witnesses of the will.
 2. A will that does not reserve the necessary share of the estate is partially invalid. Article 19 of the Inheritance Law stipulates that a will should reserve the necessary share of the estate for heirs who lack the ability to work and have no source of income. According to Article 37 of the Opinions, if the testator does not reserve the share of the estate of a successor who lacks the ability to work and has no source of income, he shall leave the necessary estate for the successor when disposing of the estate, and the remaining part may be disposed of according to the distribution principle determined by the will. Whether a successor lacks the ability to work and has no source of income shall be determined according to the specific circumstances of the successor when the will takes effect.
 3. Other invalid or partially invalid testaments According to Article 22 of the Inheritance Law, a will made by a person without capacity or with limited capacity is invalid. A will must express the true will of the testator, and a will made under duress or deception shall be invalid. A forged will is void. If a will is tampered with, the tampered contents shall be invalid.