When a sales order comes into ecomdash from the marketplace your product's Warehouse Quantity in the product details is reduced.
If you have multiple warehouses set up in ecomdash then the Warehouse quantity that is reduced is based on the priority you have set up.
If Warehouse A is priority 1 then the quantity will get reduced from that warehouse. Once Warehouse A has a warehouse quantity of 0 if an order comes in for the product then we will roll over to Warehouse B or priority 2 in ecomdash and reduce the quantity from that warehouse.
The warehouse priority level can be set at the product level by navigating to Inventory > Inventory Management > Product Details
The priority level can also be set at the company level by navigating to Settings > Warehouse Setup > Multi Warehousing. There you are able to set the warehouse priority level for your warehouses