Once such a link is requested, a DatasetDataGroupRelation object is created
and the owners of the DataGroup are asked to approve the relation. If they
approve, the corresponding permissions on the Dataset are granted to the
DataGroupUserGroup of the DataGroup. If the DataGroup owner
rejects, the DatasetDataGroupRelation is deleted.
As all owners of parent DataGroups are contained in the
DataGroupUserGroup (see link-datagroups), they also get the relevant