I would like group result

I have this request :

sourcetype="accouting" fichier="*.log" | stats count by fichier

Here is the result :

fichier count
DIAEAEF*.log    7
DIAEAU97*.log   1
DIAEHAB*.log    5
DIAEHF*.log 9
DIAEPJ*.log 5
DIAEWF*.log 2
DIAEHP*.log 2

And I'd like to gather some files to have another table as follows :

paquet  count
AA  12
BB  6
CC  13

Explain :

AA = DIAEAEF*.log + DIAEHAB*.log
BB = DIAEAU97*.log + DIAEPJ*.log
CC = DIAEHF*.log + DIAEWF*.log + DIAEHP*.log

sorry for my english... thanks google translate ;-)