As stated in my previous reply, dot-walking for task assignment is not supported in Data Manager certification policies today.  While we plan to add support for this soon, we haven't pinned down a timeframe.  You can continue to use the legacy Data Certification application for this particular certification scenario.

Regarding the scenario where a user is a manager of multiple groups, Data Manager will create a single task for the user and associate the related records with the task.  Record-to-task grouping and assignment is available for all Data Manager policy types.