1. Provide relevant certification materials: if he has died, he can provide his death certificate or cancellation certificate. If they have never registered in the household registration book, then you need to provide their birth certificate, marriage certificate or proof of kinship and other related materials.
2. Apply to the public security organ where the household registration is located: with the above-mentioned supporting materials, apply to the public security organ where the household registration is located, fill in the relevant forms and submit the application.
3. Waiting for review: After submitting the application, the public security organ will review the materials you provided. If approved, they will add the information of grandparents to your household registration book.
It should be noted that there may be differences in household registration management regulations in different regions, and the specific operations may be different. When dealing with this kind of problem, you can consult the local household registration administration for more accurate information and specific operation procedures.