Christoph Rosenmueller, Middle Tennessee State University, has published Two Kingdoms in a Multi-Tiered Empire: New Spain and New Galicia in the Mid-Eighteenth Century as Max Planck Institute for European Legal History Research Paper Series No. 2018-10. Here is the abstract.
This article casts light on the structure of the Spanish empire by focusing on the relations between two American kingdoms, New Spain and New Galicia. New Spain comprised the heartland of colonial Mexico, and New Galicia lay to its northwest. New Spain enjoyed significant status and to a degree controlled New Galicia and other dependent realms. By the mid-eighteenth century, the viceroy of New Spain sent inspectors, appointed treasury officials, and even wrested the mining camp of Bolaños from New Galicia. Yet New Galicia insisted on its autonomy. Its president resisted the viceregal interventions and finally succeeded in recovering jurisdiction over Bolaños. The relationship between the two North American kingdoms therefore differed from that between other constituent regions of the empire. The kingdom of Quito, for example, was fully subordinate to the Peruvian viceroy in Lima. The empire can therefore be described as multi-tiered and not exclusively characterized by the hegemony of Madrid/Castile over its overseas possessions. Instead, the empire consisted of uneven and overlapping ties between a group of core kingdoms and their dependent territories, and their relations changed over time.Download the article from SSRN at the link.