[Add an animated gif, add other elements, and save as animated gif?]

I'm trying to create an image that has an existing animated gif file.  If I drag in the gif and create it as a layer, it doesn't retain the animation.  

 

I did drop the Animated Image plugin dll to the FileTypes folder, but if I go to save the file, it doesn't have the .agif option.  

 

is there a way to retain the animation of the gif and then save it as an animated gif?