Current implementation relies on valid cross-reference offsets in the PDF documents so that PDF objects are easily found and parsed. However, we can implement a mechanism for repairing documents with invalid cross-reference tables. The attached project shows how to repair the simplest case of cross-reference table by using RepairDocumentWithSimpleCrossReferenceTable method.
When merging files that contain the "159 '\u009f'" char, ArgumentException("The encoding is not supported.") is thrown.
Currently, PdfStreamWriter writes only PDF pages. If we implement API for merging multiple pages or whole documents we would be able to preserve links between pages (which are currently being corrupted). Merging whole documents would also allow preserving document properties (bookmarks, interactive forms, ...). For a more detailed list of the unsupported document properties you can refer to our documentation: https://docs.telerik.com/devtools/document-processing/libraries/radpdfprocessing/formats-and-conversion/pdf/pdfstreamwriter/features. We may also implement API for adding initial document properties from some existing PDF file.
Trying to clone the Signature of a SignatureField leads to InvalidOperationException as the FieldName of the cloned signature is already set.