.NET PowerPoint Library - Merge PowerPoint Presentations with C#

using Syncfusion.Presentation;
//Open an existing source presentation
using FileStream sourceStream = new FileStream("SourcePresentation.pptx", FileMode.Open);
using IPresentation sourcePresentation = Presentation.Open(sourceStream);
//Open an existing destination presentation
using FileStream destinationStream = new FileStream("DestinationPresentation.pptx", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
using IPresentation destinationPresentation = Presentation.Open(destinationStream);
//Iterate each slide in the source and merge it into a presentation
for (int i = 0; i < sourcePresentation.Slides.Count; i++)
{
    //Clone the slide of the source presentation
    ISlide clonedSlide = sourcePresentation.Slides[i].Clone();
    //Merge the cloned slide into the destination presentation
    destinationPresentation.Slides.Add(clonedSlide, PasteOptions.UseDestinationTheme, sourcePresentation);
}
//Save the PowerPoint presentation
using FileStream outputStream = new FileStream("Result.pptx", FileMode.Create);
destinationPresentation.Save(outputStream);