Hi,
the second datasource seems to contain material master data, so I would suggest du load them into the attributes of the material infoobject. Then you add the material to the dso where you load the data from first datasource. You can use the data from second datasource as navigational attributes or load them to the dso in a end routine of the Transformation from datasource 1 to the dso if you need the attributes there.
Regards,
Simon