Princess Solaris and Princess Mondlichtina are Princess Celestia and Luna's other other nieces. Their sister, Cadence is older then them. Solaris is 17 years old, while Mondlichtina is 12. Princess Cadence, however, is probably in her mid 20's. The younger sister, does not have her cutie mark yet and the middle has a cutie mark, a solar eclipse.
Before Mondlichtina and Solaris were born, Cadence couldn't wait for her aunt's niece to come. More info soon.