Could you please suggest on how to dynamically change the report name in case of multiple document report?

If we select multiple records from the tree view and print the report, I do not get the value i set in "print_report_name"

Please suggest a solution

My requirement is to append the current date with the name of the report

like Report_name_Tue Jul 28 13_26_10 2020.pdf. Please note its not a single doc, but multiple documents