This program is written to work with it own sample-set or with Ste-Anne mosly sample-set which have single releases. You can replace myco sample by your own sample but it is not the goal of this software and i do not know what will happen with multiple release. My program only writes a file that is the description of the custom organ, description called a CODF; that is a text file you can edit. If Hauptwerk allows custom organs to have multiple releases, I think there is no reason for Myco cannot do it.
JP