John,
The issue with doing the order to decrement inventory is approving it; thus overstating sales. Or are you doing a zero dollar order? I Which will throw off the margin reports (if they look at them) and still hit COGS (so COGS is now overstated and they need to back that out). If they do a cost order and pay it with a special payment method they would have the total for the JE to reverse the ale and cogs impact; but it still messes with the reports. The reason for a 2nd database is so they can easily see how much inventory is at the main site and at FBA and avoid these other issues.
I agree with you that they HAVE to decrement inventory when they send it to FBA; it's just a matter of how they do it. They can also replicate the SKUs and then re-allocate - however we run into challenges with this as well. If they have more than a handful of SKUs it can be labor intensive and get messy (the inventory table can get out of whack pretty good) - plus they still can't easily see the inventory value at both places without exporting the report and filtering it.
Using one DB is ok if they don't have many SKUs or are not doing a lot of business thru FBA; otherwise I still would recommend a 2nd database. This also allows you to easily break out the sales, cogs, inventory and AR in QBs - best of all worlds.
With all of the above; can you give the user an option of having the orders come in like normal?
Thank you!
Rox :-)