Hi,
Thank you for your interest in Syncfusion products.
You can merge several PDF documents into a single document as shown in the sample located below:
My Documents\Syncfusion\EssentialStudio\7.2.0.37\Windows\Pdf.Windows\Samples\2.0\Modify Documents\Merge Documents\
You can check the online version of this sample in the link below:
http://samples.syncfusion.com/ASPNET/7.2.0.37/web/Pdf.Web/samples/3.5/Modify%20Documents/Merge%20Documents/cs/default.aspxPlease try this and let me know if you have any questions.
Regards,
Geetha