Концепт слабкого суб’єкта сімейних правовідносин та пріоритетність його прав та інтересів в договірному регулюванні відносин між матір’ю, батьком і дітьми

This article is devoted to the examination of the specific legal status of the child within the framework of family legal relations and their legal connection with other subjects of such relations. The doctrinal concept of the vulnerable subject in family legal relations is introduced, alongside the principle of priority of their rights and interests. The article outlines the essential characteristics of the vulnerable subject and presents an authorial legal definition of this category. A vulnerable subject of family legal relations is defined as a participant whose ability to independently meet their needs is limited due to a range of objective and subjective factors, including but not limited to: age, developmental stage, health condition, educational obligations, incapacity for work, and financial status. The existence and development of such a subject are dependent on other participants in family legal relations. This dependency results in an inherent inequality in their ability to acquire and exercise rights and obligations. This inequality is compensated for by a legally established mechanism through which the interests and rights of the vulnerable subject are prioritized over those of other participants. This normative preference is embedded in legislative acts enacted by the state regulator. The scope of the concept of the vulnerable subject has been expanded to include not only children but also other legally dependent participants in family relations, such as incapacitated adult sons or daughters, incapacitated parents, and adult children who continue their education. It is determined that the prioritization of the interests of the vulnerable subject constitutes a fundamental principle governing the contractual regulation of family relations between mother, father, and children. It is argued that the limits of contractual autonomy of the parties–namely, the mother, father, and children–are to be construed and applied with regard to the necessity of safeguarding the rights and interests of the vulnerable subject within such legal relations. In view of the material legal influence exerted by the concept of the vulnerable subject upon the framework of contractual regulation between mother, father, and children, the article proposes an original legal definition of the conclusion of agreements between mother, father, and children, identifies the distinctive features of such agreements, and formulates the doctrinal understanding of their termination. Furthermore, it is established that even in cases where a contract between mother, father, and child is declared null and void, the rights and obligations of the parties–which were not properly governed due to the defectiveness or invalidity of the contract–remain in force to the extent determined by the applicable legislative provisions. An original definition of the “functions of agreements between mother, father, and children” is formulated. The article also presents an authorial classification of the primary legal functions of such agreements, developed through the analytical lens of the vulnerable subject doctrine. It is demonstrated that, in performing their consolidating function, agreements between mother, father, and children serve to maintain the stability of family relations by balancing the rights and interests of the participants. This balance is structured around the primacy of the child’s interest, as parents are legally obligated to care for and support their children. Over time, this legal dynamic evolves: adult sons or daughters may become obligated to support incapacitated parents in need. Thus, within the legally significant relationship of mother–father–children, a process of intergenerational transmission of the vulnerable subject status occurs, whereby the interests of the vulnerable party retain their priority across generations. This legal construct ensures both the internal balance and continuity of familial relations and the overall social cohesion and systemic stability of society at large.