合并docx文件后，标题1、标题2没有在样式带中突出显示

我正在合并一些docx文件，这些文件是通过c#使用openxml和wordml创建的。那些有标题标签的文件，如标题1，标题2等，以及一些带有这些标签的文本。当这些文件被单独创建时，如果我们点击或选择那些标记为标题1和标题2的文本，那么标题1，标题2等会被突出显示，导航盘也会显示这些标题1，标题2标签，但是合并这些文档后，当我们点击或选择这些文本时，标题1和标题2不会被突出显示。在风格丝带。合并的代码在这里，

        MemoryStream ms = new MemoryStream();
        using (WordprocessingDocument myDoc =
WordprocessingDocument.Create(ms, WordprocessingDocumentType.Document))
        {
            MainDocumentPart mainPart = myDoc.AddMainDocumentPart();
            mainPart.Document = new Document { Body = new Body() };
            int counter = 1;
            foreach (var sectionOutput in sectionOutputs)
            {
                foreach (var outputFile in sectionOutput.Files)
                {
                    Paragraph sectionBreakPara = null;
                    if (!sectionOutput.SectionType.Equals(sectionOutputs[sectionOutputs.Count - 1].SectionType))
                    {
                        if (outputFile == sectionOutput.Files.Last())
                        //check whether this is the last file in this section
                        {
                            using (
                                WordprocessingDocument pkgSourceDoc =
                                    WordprocessingDocument.Open(outputFile.OutputStream, true))
                            {
                                var sourceBody = pkgSourceDoc.MainDocumentPart.Document.Body;
                                SectionProperties docSectionBreak =
                                    sourceBody.Descendants<SectionProperties>().LastOrDefault();
                                if (docSectionBreak != null)
                                {
                                    var clonedSectionBreak = (SectionProperties)docSectionBreak.CloneNode(true);
                                    clonedSectionBreak.RemoveAllChildren<FooterReference>();
                                    clonedSectionBreak.RemoveAllChildren<HeaderReference>();
                                    sectionBreakPara = new Paragraph();
                                    ParagraphProperties sectionParaProp = new ParagraphProperties();
                                    sectionParaProp.AppendChild(clonedSectionBreak);
                                    sectionBreakPara.AppendChild(sectionParaProp);
                                }
                            }
                        }
                    }
                    string altChunkId = string.Format("altchunkId{0}", counter);
                    AlternativeFormatImportPart chunk = mainPart.AddAlternativeFormatImportPart(
                        AlternativeFormatImportPartType.WordprocessingML, altChunkId);
                    outputFile.OutputStream.Seek(0, SeekOrigin.Begin);
                    chunk.FeedData(outputFile.OutputStream);
                    AltChunk altChunk = new AltChunk(new AltChunkProperties(new MatchSource { Val = new OnOffValue(true) })) { Id = altChunkId };
                    mainPart.Document.Body.AppendChild(altChunk);
                    if (sectionBreakPara != null)
                    {
                        mainPart.Document
                           .Body
                           .AppendChild(sectionBreakPara);
                    }
                    counter++;
                }
            }

            mainPart.Document.Save();
        }
        return ms;