How to Change Orientation of Single Paragraph or Page using Open XML and C#?

I am generating a word document using C# and Open XML SDK. I want to change the orientation of some paragraphs and their containing pages to landscape while keeping the other ones in portrait orientation.
I tried some solutions, but they didn't achieve what I am looking for and instead the orientation of all the pages have been changed to landscape except the first one. These solutions include:
- Adding SectionProperties to the paragraph that I want to change its orientation to landscape:

WordprocessingDocument WordDocument = WordprocessingDocument.Open(ReportFile, true)
Paragraph paragraph =  new Paragraph(new ParagraphProperties(
               new SectionProperties( new PageSize() 
               { Width = (UInt32Value)15840U, Height = (UInt32Value)12240U, Orient = PageOrientationValues.Landscape })));
WordDocument.MainDocumentPart.Document.Body.Append(paragraph);

- Adding a new Body to the main document and appending the paragraph to it:

WordprocessingDocument WordDocument = WordprocessingDocument.Open(ReportFile, true)    
Body body = new Body();          
Paragraph paragraph =  new Paragraph(new ParagraphProperties(
               new SectionProperties( new PageSize() 
               { Width = (UInt32Value)15840U, Height = (UInt32Value)12240U, Orient = PageOrientationValues.Landscape })));
body.Append(paragraph);
WordDocument.MainDocumentPart.Document.Append(body);

- Adding a new Body to the main document and appending SectionProprties to it directly:

WordprocessingDocument WordDocument = WordprocessingDocument.Open(ReportFile, true)  
Body body = new Body();
Paragraph paragraph = new Paragraph();
SectionProperties sectionProp = new SectionProperties(new PageSize() { Width = (UInt32Value)15840U, Height = (UInt32Value)12240U, Orient = PageOrientationValues.Landscape });
body.Append(paragraph);
body.Append(sectionProp);
WordDocument.MainDocumentPart.Document.Append(body);

So, is there a way for changing the orientation of a single paragraph/page?

Solution

You have to put a next page section break to begin a new section, and set the orientation for that section. Once you are done, start a new section with the default page orientation.

Next page Section Break to start landscape orientation:

doc.MainDocumentPart.Document.Body.Append(
    new Paragraph(
        new ParagraphProperties(
            new SectionProperties(
                new PageSize() { Width = (UInt32Value)12240U, Height = (UInt32Value)15840U, Orient = PageOrientationValues.Landscape },
                new PageMargin() { Top = 720, Right = Convert.ToUInt32(rightmargin * 1440.0), Bottom = 360, Left = Convert.ToUInt32(leftmargin * 1440.0), Header = (UInt32Value)450U, Footer = (UInt32Value)720U, Gutter = (UInt32Value)0U }))));

Next page Section Break to start portrait orientation:

doc.MainDocumentPart.Document.Body.Append(
    new Paragraph(
        new ParagraphProperties(
            new SectionProperties(
                new PageSize() { Width = (UInt32Value)12240U, Height = (UInt32Value)15840U },
                new PageMargin() { Top = 720, Right = Convert.ToUInt32(rightmargin * 1440.0), Bottom = 360, Left = Convert.ToUInt32(leftmargin * 1440.0), Header = (UInt32Value)450U, Footer = (UInt32Value)720U, Gutter = (UInt32Value)0U }))));