GID depends on lowest node Id not originating group

It appears that if you create content in a group that has a group audience ID of say 33, its Group ID will also be 33. But if you add ANOTHER group to the Group audience with a LOWER GID say 25, then the Group audience is 33, 25 but the GID always defaults to the lowest GID 25 rather than the original GID. I am looking for a way of recording in which group the content originated but that seems to get overridden once a new group gets added with a lower GID