Children apply for American green cards for their parents. What written materials should parents prepare?

Hello, China applicants (parents) need the following information: 1) parents' birth notarization, 2) parents' marriage notarization or marriage certificate notarization, 3) parents' divorce notarization or divorce certificate notarization, and 4) parents' death notarization if one parent is no longer alive. All the above documents are necessary. When we submit, we need to add corresponding documents according to the background and personal situation of different applicants.