In FRS How to sum multiple members and show them in 1 row with the ability to expand to child values

I'm attempting to create a P&L in FRS and have selected multiple natural accounts in member selection.  The report shows a row for each account.  I would like it to show the sum with the ability to expand to the individual accounts.  I'm trying to avoid creating a new hierarchy as this will only be used for 6-8 weeks.