Some systems allow you to have a "buffer" or fudge factor on minimum stock quantity. This is in place to ensure customers can not purchase a product that is close to its lowest stock level.
TranslatorHQ does not need this vague buffer as it is a live system and is designed to be always up to date.
If you want to allocate only certain stock to online you can do this on each product using a different source group. You can then use Retail Express's multiple outlets to transfer stock to an online outlet. This is NOT recommended as it removes the ability to easily sell all your stock but some stores like this high level of manual control. You can then maintain your own "buffer" in your normal stores and only a level of inventory on your products that you want to be made available.
For example, if you want a "Minimum Stock Buffer" of 5 for a product then leave that stock in your warehouse and only transfer stock to your online warehouse above this 5 limit.