Content can be auto-fetched for groups of records from some other applications. This is not a sync mechanism.
Multiple watched groups are allowed though be mindful heavy use of this feature may affect overall performance - i.e. the feature is not designed as a fully-synced system but rather for importing/updating some DEVONthink data.
A receiving container for the group's data is always added at root level in a document (and should not be moved elsewhere). This is for necessary design considerations re performance.
There is currently one form of watched group: