Tempo Change Audio Issues

Hi,

Being new to Cubase Pro 8, I have been going through the learning curve. I have a tempo problem which I will try to describe and would appreciate some help. I’ll use a simple example as an illustration. Let’s say I have a 10 measure long song with 2 audio tracks. Each audio track has an imported audio file (wav) in it, and the 2 tracks are in “sync” and the timing is fine between these 2 instruments. Track 1’s audio is 5 measures long, starting at measure 1. Track 2’s audio file is 2 measures long, starting at measure 6. I want to reduce the tempo from measure 4 to measure 9 from 140 to 130. When I do this, these 2 measures are no longer in sync. So I think my question is - does the length of ALL audio in this song have to start before measure 4 and extend beyond measure 9 for these 2 tracks to stay in sync when I change the tempo? I have to believe this is a common problem that I do not have experience with (yet). If none of this is clear I can post a screen capture if it helps. Thanks for your feedback on this!