Again, this is one of my favorite poly ships!
 
Flash Sentry and Sunset Shimmer did date previously to her leaving through the portal, and it did not end well. A few years later, Flash met Moondancer when they literally crashed into each other. The Royal Guard felt terrible, and took the rest of the day to get to know her, and slowly cracked through her cold demeanor. When Twilight, Ex of Flash and friend of Moondancer, found out, she was ECSTATIC. she would plan dates for the two and probably would’ve done their wedding if her wife Fluttershy didn’t stop her.
 
Then Sunset returned to Equestria and saw Flash, whom she had returning feelings for in the other world, and went up to him. It was awkward, and he was dating someone else, but when Sunset met Moondancer, well…more feelings arose. She went to Fluttershy to vent, and she told her to just…go for it. Mean while, FLash had been thinking about the past, and was talking to Moondancer about her. They still loved each other, but Moondancer knew he was still in love with her, and offered to break up so he could be with her, but Flash loved Moondancer. and well, Moondancer found the other unicorn to be very pretty. What if…What if they asked her out? You can guess what happened there, and they remain to be one of the most strongest poly herds there are, and they have a little pegasus bab named Beautiful Daydream, or Beau, whom they adore with all their hearts.