In the good old data grid it was possible to select a one to many association and then select a string or enum field for the object over the one to many association. The chosen attributes for the objects that where found over the assocation would be concatenated together. In Data Grid 2 this is not an option and you would have to make a temporary object or an extra attribute to hold the concatenated value. Example:
Object team has an assocation Account_Team with three accounts. (account 1: Harry, account2: Peter, account3: Dave). In data grid you could show a list of teams and for every team show the members by chosing the account_team associatoin and then the name association. In the column then the string: “Harry, Peter, Dave” would be shown for this team.