At the moment, the area of Bonaire, Sint Eustatius and Saba in MusicBrainz stands without any links to subdivisions or a parent sovereign country despite each of them existing. This area is made of the islands of:

• Bonaire 
• Sint Eustatius
• Saba

As a whole, it is part of the Netherlands (the country in narrower sense, NOT the eponymous Kingdom of the Netherlands ¹.
 
In my opinion the relationships between the aforementioned should be reorganized so that:

• The collective area for the 3 islands (BES) is placed under the Netherlands as its part (alongside the provinces that make up the European mainland).
• The individual areas for each of the 3 islands are moved from being parts of the Netherlands to being parts of BES islands

¹ I know I'm not the best person to explain the make-up of the kingdom or the Netherlands or the relationship between its European mainland and the Caribbean territories, but the Euler diagram on the following link does so very neatly: https://www.reddit.com/r/europe/comments/3e1j41/euler_diagram_of_the_kingdom_of_the_netherlands/