Hi,
In that case that would require first to check that the solution you're using for your physical sales has an API so that the stock can be updated from a website. That might not be the case.
If that's the case, then it will require the development a plugin of the group "hikashop", implementing the onAfterOrderCreate/onAfterOrderUpdate triggers of the HikaShop API:
www.hikashop.com/support/documentation/6...r-documentation.html
in there, you would get the data from the order and send some kind of API call to your physical store software API so that the stock can be updated (the code to write in there will depend largely on the API of that software and you'll need the developer documentation from your solution provider).