[Kennel]

Go to the Forgotten battles folder in your hard drive

open it

locate the config file ( its a notepad file with a cog on it)

open it

This file is full of data that alters in game settings, find the section under the heading [game] add the following line
HakenAllowed=1

this enables the swastika on the tailplane of the German aircraft as well as correct finnish markings

this is how my [game] section of the config fike looks

[game]
Arcade=0
HighGore=0
mapPadX=0.6376953
mapPadY=0.0065104165
viewSet=34
Intro=0
NoSubTitles=0
NoChatter=0
NoHudLog=0
NoLensFlare=0
iconTypes=3
eventlog=eventlog.lst
eventlogkeep=0
3dgunners=0
SubTitlesLines=2
ClearCache=1
TypeClouds=1
HakenAllowed=1

hope this helps