Ok, my problem is solved:
Components are defined in records.ini, too.
in case anyone else has this problem at some point:
Code:
[Record1]
Type=FreeArc_Original
Source={src}\Data1a-01.bin
Output={app}\
Disk=1
Size=386.315.748 bytes
[Record2]
Type=FreeArc_Original
Source={src}\Data1b-01.bin
Output={app}\
Disk=1
Component=1
Size=712.924.910 bytes
[InstallerSettings]
SingleDisk=1