Yalin,
since you already have the index file you can use a pipe as following. Assume your index file is named 'fbackup.index', then type, e.g.
awk '{print $3}' fbackup.index | cut -f -4 -d '/' | sort -u
In this way you get all backuped files or directories up to the 3rd level. Increase the argument (-4) of option -f to get more levels listed, or decrease it to get less levels listed.
no users -- no problems