soheechul is just a brother-sister relationship ^^!
JYP is the largest shareholder of J.tune Ent now, b/c Rain is enlisting for the army in 2011 ( i think ). So, Mblaq and other artists under J.Tune are now under JYPE. Which means, they are also JYP Nation. Even though they might just be a sub group under JYP like Cube Ent, they’re all still part of JYP Nation. (: