Although digital watermarking has been a well-researched topic for the past decades and has seen numerous implementations for relational databases, it still lacks research for non-relational schema-less databases. In this paper, we explore proposed techniques for non-relational database watermarking and introduce an improved technique for NoSQL database watermarking. The improved technique produces pseudo documents, embeds a watermark in them, and inserts them into the database. Then it modifies the relations between the pseudo and real documents to indicate which documents are covered by the watermark. Lastly, the pseudo documents act as a cover for the watermark embedding, proving the authenticity of the documents connected. We tested the technique against numerous modification and deletion attacks. The results show that the introduced technique does not improve the robustness of the watermark. Although the technique has the potential to produce a robust watermark, it still needs to be improved before being used in a commercial setting.