Underage children do not need to be present. They do not have the right to sign, and their arrival is in vain. Since buying a house is a major event, no one under the age of 18 has the right to sign. Even if someone over 16 has an ID card, There is no right to sign. If the signature is signed by the legal guardian or designated guardian (for example, the child's parents are the legal guardian), you must bring the child's birth certificate or ID card, or the household registration book that can prove the guardian's ID card (the household registration book must reflect the The relationship between the parents is enough, otherwise you need to apply for a household registration certificate). The new version of the birth certificate has the names and ID numbers of the parents, so there is no need to provide the household registration book