Phil, it's really cool! Think Msword, and copy and paste.
Open both files, copy one to the clip board, switch to the other file, with
control-f6, and from the edit menu, you can paste to the beginning, finnish
point or end of the file. I haven't tried pasting in to the middle of a
file, but their is a paste option, so I bet you could do it. I just use it
to make album sides in to one file, before I split the file in to individual
song tracks.