Garageband workaround: Tempo change post-recording? Is there a way to change the master tempo in Garageband after you've already recorded some audio tracks?  

Use case:


Create analog audio tracks (e.g. record guitar, voice, etc.)
Manually figure out the tempo of the recorded audio
Set the master tempo to this value
Add a drummer track which plays at this tempo


Any time you change the master tempo, it re-times all the tracks, which is exactly NOT what I want it to do.  I want it to not touch my analog audio tracks, and just add a drum track at the tempo I specify.

I realize Garageband isn't really intended for use as a DAW, but this seems like such a simple -- and common -- use case.  Yes, I know I could create the drum track first and pay along with it;  but that's not the question.

Any ideas?
Turns out there's a simple answer:  all this is supported in Logic.  Garageband and Logic are the same piece of software;  Garageband is the limited version.

I upgraded to Logic after being frustrated with this (and many other limitations).  It was well worth it.