There exists a composite sample set that utilizes Piotr Grabowski's Friesach and Cracow sample sets, but it appears it is currently only available for use on Hauptwerk.
http://www.nightbloomingjazzmen.com/Les_Friesach-Cracov_Organ.html
Would someone be willing to make a GrandOrgue compatible ODF for this composite set? I have no knowledge pertaining the subject on how to do it myself.