What does this question mean? "Refer to existing event(s)?"
This screen allows you link to the document you are filing to a previously filed, related document. By clicking the box next to "Refer to existing event(s)?" the system will provide a list of documents already filed in the case. You can narrow that search by entering a date or document number range. You would then click the box next to the document you wish to link to. You may bypass this screen if there are no previously filed documents to which your filing relates.