New Post: Mosaic different size images

I'm trying to add a small image to a blank canvas, and then overlay a translucent background image (the same size as the canvas) over all this. And then output as a .gif file.

Here' the code I'm using, the file I get in the end is just the smaller sized image.

                    using (var images = new MagickImageCollection())
                    {

                        using (var canvas = new MagickImage(new MagickColor(Color.Gray), 300, 300))
                        {
                            smallImage.Resize(90, 90);
                            var smallImageDraw = new Drawables();

                            smallImageDraw.Draw(smallImage);
                            smallImageDraw.Point(100,100);
                            smallImageDraw.Rotation(-50);
                            canvas.Draw(smallImageDraw);

                            images.Add(smallImage);

                            var bgImage = new MagickImage(FileSystem.GetFullPath(frameData.Item.FilePath));

                            var bgDraw = new Drawables();

                            bgDraw.Draw(bgImage);
                            bgDraw.Point(canvas.Width, canvas.Height);
                            canvas.Draw(bgDraw);

                            images.Add(canvas);

                            images.Mosaic();
                        }

                        using (var frameMs = new MemoryStream())
                        {
                            images.Write(frameMs, MagickFormat.Png);
                            frameMs.Position = 0;
                            var fileName = string.Format("layers/{2}-{0}-{1:dd-MM-yyyy-hh-mm-ss}.png", Guid.NewGuid(), DateTime.Now, frameData.Index);
                            FileSystem.AddFile(fileName, frameMs);
                            gifFrames.Add(fileName, frameData.Item.Delay);
                        }                      
                    }                

Is sometihng being done in the wrong order? Or is Drawable the wrong thing to be using?