Hi Leon, there is no pure way to do that across all groups. The premise of a group is that it has unique properties (config, profiles, IP's etc) that are different and thus require a different management group. Otherwise you'd have one group and one global config.
That said, if the baseline of your config is the same - I'd consider making a new group via templates then importing the config from an existing device - then edit your group specific variables. At this point you could enable IGC by editing the group management values.
Cheers, Adam