CDT relations

I establish a One-to-One parent-child relationship in Appian by including a reference field for the child Custom Data Type (CDT) within the parent CDT during creation. Although the parent CDT is successfully published in the database, initially, the child lacks a primary key. Appian generates the primary key in the child after publication, associating it as a foreign key in the parent table. However, an issue arises during parent  table updates; instead of updating the child table, it consistently creates new records. Recognizing this is likely due to the absence of a primary key in the child CDT, I added the necessary primary key during the update of child table  and the child table continues to create new records rather than updating existing ones. Seeking a solution for this behavior.