Finally I managed to do it like you both said with a surrounding data view, around my datagrid, and by creating a link between my hub entity and my object, in order to put the source as an association between the 2.
Thank you both for the help.
Why is 'hub' an attribute in this case?
If you create an entity for it and associate all of your accounts with the hub, you can simply retrieve all accounts with the same hub entity as the current user.
determine the owner of the current user and pass that owner object in a surrounding dataview, limit the account list by using the dataview object (currentobject). This is pretty much the same solution as suggested by Larn ;)
Does someone have an idea to access to these attributes in XPath ?