Oh dear I’m really struggling!!
I tried to select all files in music mode in the pool and then timestretch but it comes out with parts playing at different times.
Thanks I alos tried your suggestion about making sure the time signature and tempo in the pool is set consistently - I did this but found that my parts have been recorded with different tempos - possibly because I had put a tempo track down that fluctuated with the live performance.
I don’t know why Steinberg make this so confusing - It’s really frustrating in that you just want parts a and b to timestretch by the same amount but it seems to be practically impossible to execute!!