using GemBox.Document; public static class GemBoxDocumentHelper { public static DocumentModel JoinWith(this DocumentModel destinationDocument, string filePath) { DocumentModel sourceDocument = DocumentModel.Load(filePath); foreach (Section sourceSection in sourceDocument.Sections) { Section destinationSection = destinationDocument.Import(sourceSection, true, false); destinationDocument.Sections.Add(destinationSection); } return destinationDocument; } }