Hi Susan:

You can't import the Control Account because a change in Costing method requires changes to the Lots and Costs (they have to be rolled up into Lot 1). The import process isn't designed to do that. It only loads numbers and strings into fields.

However there is a solution (again I have to give credit to Steve Schwartz). Do you have ACCPAC Plus Inventory Control 6.5? If you do, you can edit the Control Account(s) and change it from FIFO to Average Costing. Once you save that change, it ripples through the inventory list and rolls everything into Lot 1.

Currently you cannot do the same thing in Adagio.

I would suggest 2 things:
1) Run Day End, Make a backup; Compare Valuation Report before & after; Run Data Integrity Check before & after
2) Talk with your accountant before changing the costing method.