Legal analysis
If the change is not the main content through negotiation between both parties, it will take legal effect if it is stamped with proofreading seal or thumbprint. The modified position is invalid without the signature of both parties to the contract; However, it is generally held that part of the contract is invalid, which does not affect the validity of other terms of the contract, unless it is the main and key terms of the contract. The validity of a contract means that the parties to an established contract have certain legal binding force, which is usually called the legal validity of the contract. A legally established contract shall take effect upon its establishment. After a legally protected contract is established according to law, its legal binding force, that is, its legal effect, shall not be changed or dissolved without authorization. Generally speaking, the contents of a contract are not allowed to be changed. A contract with altered marks must be confirmed by the parties to the contract, otherwise the altered contract will be regarded as invalid or partially invalid. Unless the altered contract is modified and sealed by both parties, the relevant benefits of the contract will not be recognized, especially in the contract between both parties, its legal effect can only be recognized after being recognized by both parties and stamped with the modified seal. This is the correct way to modify the contract.
legal ground
People's Republic of China (PRC) Civil Code
Article 490 Where the parties conclude a contract in the form of a contract, the contract is formed when the parties sign, seal or fingerprint it. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it. A contract shall be concluded in written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.
Article 543 The parties may modify the contract through consultation.