Hi Martin,
Thanks for contacting Syncfusion support.
Query 1: How can i complete this code to add Export features like (Excel-Pdf-Word).
We have already discussed about your requirement in the following kb.
Query 2: how can i add third level child grid (i already had 2 level)?
We have created js playground sample in hierarchy grid with three level.
For more information, please refer to the following UG Link.
Regards,
K. Karthick