Sync the two through iTuunes, I do it all the time. You can use multiple time sigs in a tune, but you must edit them into the tune. I have a song in 6/4 with a 4/4/ bridge. To get the feel I wanted, I had to write it as a series of 4/4 bar-2/4 bar, 4/4-bar, 2/4-bar, etc. till the bridge, But it compiled and plays just fine, it's on my new CD (at least the midi tracks are...)