Can you specify more exactly where you can find it on the wiki site? It is a bit long…

Anyway, inside a multipolygon is not needed any additional relation. One or more simple ways are fairly enough.

Look e.g. here:
• https://www.openstreetmap.org/relation/1775846 or 
• https://www.openstreetmap.org/relation/1775847

They consist of two ways and that's it. No additional multipolygon inside the multipolygon.