Hi
Insert a group on DetailID and use below formulas :
//Place the below on your group header
Whileprintingrecords;
Stringvar ft:=' ' ;
//Place this formula in detail section
Whileprintingrecords;
Stringvar ft:=ft+'/'+From;
//Place below formula in your group footer
Whileprintingrecords;
Stringvar ft;
Now this group footer will display A/B/C/D/E , add group name before to it and suppress all sections except group footer.