I gained a fondness for using img2img after the initial txt2img in order to refine the details and make something greater than AI does on its own. In this case I had a horrible output for the filly and manually masked and cropped the image in order to generate her separately to combine the two.

Partial prompt:
derpibooru, (golden harvest), safe, (solo), holding filly, mare, portrait, foal, [[adorable]], pony, adorable, [[[[[[chibi]]]]]], (precious), girly, heartwarming, dutch golden age, Getty Images, victorian, looking at you, looking forward