Chrysalis and some of her changelings were watching the sad scene where Rainbow Dash had to head back home and leave her dad behind. She must've realised that since that storm had sent her to the human world and how that man found her and raised her from a filly that the storm gave her amnesia. This might be part of some sort of plan for revenge on the ponies, but mostly Twilight, Shining Armor, and Cadence, by using Rainbow Dash's human father.

Chrysalis: So one of Twilight's friends had been raised by that human all that time. Must be the rarest love to feed off of since she must meant a lot to the boy. I do believe we can make this father and adobtive daughter bond work to our advantage boys.