The spouse, parent-child, and sibling subsystems are critical components in the dynamics of multi-child families, collectively contributing to family differentiation and cohesion. This study employs a person-centered approach to explore the interdependence among these subsystems in Chinese multi-child families in Shandong Province. Additionally, it examines the relationships between subsystem patterns and two key outcomes: parental burnout and adolescent loneliness. Data were collected through a survey of 547 adolescent-parent pairs, all from intact, first-marriage, multi-child families. Using latent profile analysis based on marital, parent-child, and sibling relationships, the study identified three distinct profiles within multi-child families: Harmonious (73.1%), Disharmonious-Spillover (20.3%), and Disharmonious-Compensatory (6.6%). Results indicate that Harmonious families are associated with the lowest levels of parental burnout and adolescent loneliness. Conversely, Disharmonious-Spillover families exhibit the highest levels of adolescent loneliness, while Disharmonious-Compensatory families experience the highest levels of parental burnout.