how do I merge files?

I finally ripped my music into digital format. It is a very large library so I performed the rips in four segments creating four folders of music. The highest level folders are Music1, Music2, Music3, Music4. The next layer folder is the artists name, then album name, then the actual MP3S.
How do I merge the folders? If I perform a copy the first artist name is sees that already is exists, the finder wants me to skip the copy or replace the folder that is there. I simply want to add the folder or merge it.
Is there a "merge" function in OSX? I tried Carbon Copy but it will not copy or sync fils on the same disk.

thanks in advance for the help

jim