Now, whilst it is easy for me to just SAY that the Sienar plot predates Episode III (and in any case, the similarities between the two are only logical for such Dark Side Masters)... and I am sure you all believe me anyway...
... but some of you may be surprised how long Sienar has hovered in the background. The name 'Kalik' is a clue, as was someone's hallucinations in the Ghost Citadel.
Bonus marks to the first person to work it out.
Incidentally, this page:
Which was the beginning of Gallagher's entry into the Sienar plotline, demonstrates that I would have had to have been quick off the mark to have copied Episode III...