Right now, Oliver POS multi-warehouse functionality is limited in that each warehouse/inventory is standalone.

So you have your default warehouse which is the same as your WooCommerce inventory and has a two-way sync with it. Then, provided you're on the enterprise plan, you can make as many warehouses as you would like, and each warehouse has the same products as in your WooCommerce store.

You should be able to set up your default/WooCommerce warehouse as the master inventory, so that each additional warehouse adds up to it.