Hello Igoler,
I guess that what you're are trying to do it pretty much what iTunes does when its allowed to consolidate your library. So I sugest you let iTunes handle your FLACs by installing Fluke, a free app which magically makes iTunes support FLAC seamlessly. Its works like a charm https://code.google.com/p/flukeformac/
Here's a tutorial on how to organize library with iTunes (aka consolidate):
http://www.switched.com/2010/11/02/itunes-consolidate-library-keep-organized/
By the way, perhaps you can make use of the solution we're figuring out here in this post :http://www.noodlesoft.com/forums/viewtopic.php?f=4&t=2176