I have been spending quite a while thinking about the grub2 menu structure and it seems some people put E2B on the 2nd partition of their USB drive instead of the first partition. I don't advise this because of the 137GB BIOS bug, but as long as the 2nd partition ends before 137GB, it should work OK.
For payload files to be detected by the grub2 menu system, they must have specific lower-case names (e.g. avg.iso, konbootx64.efi). Files with names such as avg_arl_cdi_all_120_150814a10442.iso or "AVG AntiVirus.iso" will NOT be detected by the default grub2 menu system.
So there will be a large list of specific payload file names which I will document at a later date. As a consequence, you can only have one version of any ISO (though you can add your own uniquely-named payloadfiles and add your own grub2 menu for it).