You can go to type of a field on sfdc digest node and select "Is Multivalue"
Have support of multivalue lookups : Aggregating data from lower grain to higher.
Go to edgemart and load data.
Add compute expression on child object.
Augment and connect parent node and compute expression node. Connect using proper fields and select Lookup Multiple Values
Update and run the data flow.
Every dataset has XMD file. which could be downloaded and uploaded.
