Hi Jörg,
From the given details, we have found that your requirement is execute nested mail merge while begin group is in header and end group is in section body.
Currently, DocIO does not provide support to perform mail merge when the merge fields of a group are in multiple text body. We have already logged this as a feature request in our database and We don’t have any immediate plans to implement this feature. At the planning stage for every release cycle, we review all open features. We will let you know when this feature is implemented.
The status of this feature can be tracked using the following feedback report.
Note: Essential DocIO will perform Mail merge for Header & footer elements too. Both Begin & End Group must be preserved in single text body to perform this.
Regards,
Lokesh B
