Split PDFs into PDF per page (which can then be edited by InkScape) and merge

PdfSplitAndMerge.cs

static void pdfSplitIntoPages()
{
    // EO.Pdf.Runtime.AddLicense("...");

    string sourceFile = @"C:\TEMP\Blah.pdf";
    var pdf = new PdfDocument(sourceFile);
    var pages = pdf.Split(Enumerable.Range(1, pdf.Pages.Count-1).ToArray());
    var i = 1;
    foreach (PdfDocument page in pages)
    {
        string newName = Path.Combine(Path.GetDirectoryName(sourceFile), Path.GetFileNameWithoutExtension(sourceFile) + " - Page " + (i++).ToString("000") + ".pdf");
        page.Save(newName);
    }
}

static void pdfMergePages()
{
    string sourcePattern = @"C:\TEMP\Blah - Page *.pdf";
    string targetFile = @"C:\TEMP\Blah - MERGED.pdf";

    var sourceFiles = Directory.EnumerateFiles(Path.GetDirectoryName(sourcePattern), Path.GetFileName(sourcePattern))
        .OrderBy(f => f);

    var newDoc = PdfDocument.Merge(sourceFiles.Select(f => new PdfDocument(f)).ToArray());

    newDoc.Save(targetFile);
}