Do I need to be married to be added as a de facto on my fiancé's Thai visa application?

The applicant inquired about the necessity of being married to be included as a defacto on their fiancé's DTV visa. The community responded clearly that to be considered a dependent on a visa in Thailand, one must be legally married. Several comments emphasized that a marriage certificate is required for all visa applications involving a dependent. It was suggested that the applicant apply for their own DTV visa since they are not married, as Thailand does not recognize defacto relationships for visa purposes.