Hi atummips
I'm not sure if I understand exactly what you mean. However, with ATUM, for now the only way to track the initial stock of a product and the current stock is using the Action Logs, as with this feature you can check all the changes made in your site.
Also, with our premium add-on ATUM Export PRO, you can do what you want manually, that is to say, exporting the initial stock before any selling, and then another export with the rest of stock.
Best Regards,
Andrea.