if I understand,
the solution is, save the original backup,
install Aqua, and save a backup (I call it "service backup), maybe you must create one account to have a backup, exit Aqua
find the folder containing the service backup and repace it with the oldest you want to restore,
open Aqua and perform the restoring.
Could be useful to create a backup-restore suite with a tool to navigate folders in both tasks (backup and restore) and numerate backup using the date, for example
Aquamail.backup_2014.08.23.01.34
2014 year
08 month
23 day
01 hour (format 24)
34 minutes
the best (but could be more spectacular than useful), select accounts to backup and restore...
With us, Kostya will never retire