The relationship between Dinky and Ditzy (Ditzy = Derpy hooves) -
It is often times assumed that Dinky is Ditzy's daughter. This is true, and yet not true. In reality, Dinky and Ditzy are in fact sisters. This is why they were both seen at the sister hooves social. However, The story is not as simple as it seems. Dinky and Ditzy's mother passed away soon after Dinky was born, and without a father to step in and help, Ditzy took it upon herself to raise her baby sister. With Dinky being so young, she would never have remember her real mother anyway, so Ditzy figured it would be easier on her little sister to assume that she was her mother, opposed to telling the sad truth to the young filly. However, Ditzy and Dinky did not compete together during the race at the sister hooves social. With Ditzys eye problems, winning would have been and impossibility and she didn't want to let her little sister down. So she asked another pony to step in to give Dinky a fighting chance at winning. However, to maintain the secrete from her younger sister, Ditzy request that no one bring up the subject. As far as Dinky knew, there was just an exception made for them.