They are not related. They are really good friends, like all of the other sailor scouts. They fight evil together but are not related.
Sailor Jupiter appears in Ep 25 in the anime, Act 4 in the manga. Check out this site below for more:
Sailor Jupiter is the fourth senshi from Sailor Moon. She is a princess of the planet Jupiter and a sailor scout who fights along with Sailor Mars, Sailor Venus and Sailor Mercury of the Inner Scouts...
In the manga Rini appears to be the closest to Sailor Pluto, for she is a solitary sailor.
5'7 - She is taller because she is (supposedly) American or European by birth