There are already three brothers and sisters in the household registration book. Can I add another sister's account now? How much does it cost?

Social problems are very complicated, and many problems are not solved according to law. I'll give you some legal advice for your reference now.

China's hukou migration policy is relatively strict, and only husband and wife, parents and children can rely on each other for hukou migration. In this situation, you can't move your registered permanent residence.

By adoption, you mean legal adoption. Our country has an adoption law, which specifically regulates the adoption relationship. The adoption law has strict requirements for adopters and adopters.

Article 4 The following minors under the age of 14 may be adopted:

(1) Orphans who have lost their parents;

(2) Abandoned babies and children whose biological parents cannot be found;

(3) Children whose biological parents have special difficulties and are unable to support them.

Article 5 The following citizens and organizations may be put out for adoption:

(1) guardian of orphans;

(2) Social welfare institutions;

(3) biological parents who have special difficulties and are unable to raise their children.

Article 6 An adopter shall meet the following conditions:

(1) No children;

(2) Having the ability to raise and educate the adoptee;

(3) Not suffering from diseases that are medically considered unsuitable for adopting children;

(4) At least 30 years old.

Article 7 The adoption of a child who is a collateral blood relative of the same generation within three generations may be exempted from the restrictions of the third paragraph of Article 4, the third paragraph of Article 5 and Article 9 of this Law, and the adoptee is under the age of 14.

Overseas Chinese can adopt children who are collateral relatives of the same generation within three generations, or they can be free from the restriction that the adopter has no children.

Article 10 If the biological parents put their children out for adoption, both parties shall adopt the children. If one parent is unknown or can't be found, it can be adopted unilaterally.

If the spouse adopts a child, the husband and wife must adopt it together.

Fifteenth adoption shall be registered with the civil affairs department of the people's government at or above the county level. The adoption relationship shall be established from the date of registration.

Article 19 A person who puts out a child for adoption shall not give birth to another child in violation of family planning regulations on the grounds of putting out the child for adoption.

You can determine whether your cousin can be adopted according to the above legal provisions and the actual situation of your family.