When creating/maintaining a multiprovider, consisting of several dataproviders, it’s hard to get an overview of the ‘linking’ of every multiprovider-‘field’ to it’s dataprovider(s)-field.
The SAP BW GUI doesn’t deliver the desired overview in one glance….you have to click on every individual field to see the way it’s linked.

By looking at the content (SE16) of table RSDICMULTIIOBJ, the multiprovider-linking will be shown as stated in the screengrab below: