Hi Levi,
Thank you for using Syncfusion support.
Essential DocIO perform mail merge in row wise manner. As mentioned earlier, Essential DocIO doesn’t have support to perform mail merge in column wise manner.
We kindly request you to share the below details, which will be helpful for us to analyze the feasibility to achieve your requirement and ensure whether the feature is valid or not.
1. Input Document
2. Expected Output
3. Data source structure used
If you have any further questions on this, please do not hesitate to contact us, and we will be happy to provide further clarifications anytime.
Regards,
Vijayasurya A