RE: Reimplementation from NAV to BC - Lot Tracking
I would say that this business use case is not new and happens often. However the decision depends on > How flexible is your end-customer in keeping this "historical" data away from their "brand new" Business central system?
If they are flexible then you should suggest them to only import the opening balances via item journal, probably a month detailing is fine but not more than that. Thereafter you can move their old database in a place from where Power BI developers can access this DB and pull reports for the past X years. Now when their BC starts operating, they'll have old data from P-Bi (Extracted in an excel) and also their current data from BC
If they are rigid and they want X amount of data, my friend, you'll be burning the midnight oil to import & reconcile but more than that even if some $ go off here or there, you're screwed big time. In this case I'd suggest the best way you have is Item Journal. I know you don't get to see your receipts and your transfers, I think that's how it works and that's the way you should follow, rather than going for any kind of a manual data insertion into ILE
Note: Most of the time accountants are concerned with what inventory transactions happened within the current FY. To them, what happened 3 years ago, is just for analytical purposes. I'd suggest to the Power-Bi way for historical data analysis and let the old DB stay as is connected with only P-BI. You can also build another report in P-BI which will fetch fresh data from their brand new BC system, this way the customers will have best of both worlds
What I see eventually happening is if you even manage to import X Years of historical data through Item Journals, 3 years down the line when their data becomes ginormous GB's into BC itself, their excels would fall to the knees and they'd be anyways looking for BI tools (Like P-BI, Tableau or jet Reports). It is important to paint this picture in front of the customer that if data analysis is all that matters, it does not matter where the data is stored, as long as it is secure
Sometimes customers can be fussy about their data but that does not mean data is not important nor does it mean that there aren't methods to tackle it. Tackle it wisely, show them the bigger picture