The paper presents a formal interpretation of possessive and reflexive-possessive pronouns in Bulgarian language using non-monotonic approach to formal logical representation. It offers a semantic network to model inflectional morphology of definite article for related pronouns using DATR language for lexical knowledge representation. The proposed encoding combines non-monotonic orthogonal semantic networks hierarchical representation and relational database approach. Finally, some conclusions about presenting inflectional morphology using non-monotonic semantic networks approach are presented.