One of my clients asked about adding a couple custom fields to the default fields in the header section of the report customization page. I can't see any way to do it but maybe someone out there has an idea? Thanks!
No, the standard header provides standard filters that are generated based on the configuration of a given org. The Date area does include custom date fields, but basically what you see is what you get. This is why there's a Filter section for each report to add additional filters. If they want to already have some fields selected, they could save it as a custom report.