They have the same basic facial features. I could say Luccia looks like an older version of Kidd. I could make any amount of connections, because they all look very similar.

And, as dod said, (SPOILER)Harle is one of the dragons, and Kidd is Schala. Kidd was very young when Harle (appearing just as she does in the rest of the game, because she doesnt seem to age) comes with Lynx to destroy the orphanage. In the SAME world, before any traveling between them

Play the whole game, and pay attention to the revelations about Harle and Kidd. They arent the same person.