You would have to set the data to some sort of parent object in a microflow first, then pass that parent object over to the form's context (data view). You would then need to apply XPath where
association_to_parent = '[%CurrentObject%]']
If you fill a grid from a microflow or over association, you cannot apply search filters, unfortunately.
All depends on your domain model :) From your text I assume you want to achieve that when a user logs in he can see his to which domain he belongs (and probably the other members of this domain) and each domain consists of one or more Processes? And why are you using microflow as datasource. If you have a person who inherits from system.user all can be achieved with references and with XPath and entity access. Could you elaborate a bit more how your domain model is constructed?