For example: We sell pet products on websiteA.com, we wish to set up a domain dedicated to upmarket dog products called websiteDogs.com and one for cats called websiteCats.com.
For now all we want is at least for the ability for three or more domains to point to one website - we can use scripts and styles to hide categories/products that are not relevant.
This will also allow us to have the same store with different colours, logos and imagery that may appeal to a younger, older or international market.
Ideally though - rather than us needing to write up scripts we would happily pay for more webstores - when creating listings we can choose which store the item is allowed to appear in (similar to how we select if the item is available to certain customer groups), letting us sell items in one or all stores.
Another example - some of our products we sell are garden related e.g. we sell tap adapters for dog fountains, we have also ventured into other garden products unrelated to pets. This feature of having multiple stores would allow us to start up a new store dedicated to garden products and not have to split inventory.