Quote - > Quote - Is there any alternative library that works hand in hand with Poser in a way that allows multiple undo?

Advanced Library does. 

Confirmed. And work very well it does too... Can autoconform and magnetise too.

Have also jumped on the up/sidegrade to Poser Pro and like the extra features - have something running in the queue manager now. Can't wait 'till PP 2010, all the new stuff from Poser 8 plus the extra functionality of an update Pro.! - the old interface of PP looks dated now compared to 8 :)