In supplementalMetadata.xml is a list of macrolanguages. Each line must specific a mapping from the predominant encompassed language to the macrolanguage. The macro language mappings are on:

For example, Bontok macrolanguage (bnc) encompasses a bunch of others:

bnc Bontok ebk Eastern Bontok
  lbk Central Bontok
  obk Southern Bontok
  rbk Northern Bontok
  vbk Southwestern Bontok

Be sure to also change the comment if making a change, otherwise it will be misleading.

In the above example case, the "most predominant" form is "lbk" (Central Bontok) with the largest population. The resulting line in the XML file would be:

<languageAlias type="lbk" replacement="bnc"/> <!-- Central Bontok => Bontok -->