A great feature would be to track which items on a Sales order have already been added to purchases orders when "Convert to Purchase Order" has been selected.  This way, you can view if an entire Sales Order has been "purchased" from your vendors.  Also, each time you create a PO from the Sales Order the items left to be ordered is less.  This way when you convert the next PO, you wont have to delete everything from it that has already been ordered OR needs to be ordered from a different vendor.

Our business does not typically stock everything out clients order so "back-ordering" doesn't make sense.  BUT when you have a 200 line Sales Order that has 30 different vendors which would require 30 different PO's it is VERY time consuming to create these PO's from Sales Orders without mistakes or tedious tweaking of every PO.

-Casey