FAQ: Are product relations one-directional?
Yes, always. In SQARP you add a related product to the main one, not the other way around.
An example where product relations could go both ways is matching pants with a top. You can add the pants as a related product to the top, and also the top to the pants. But in other cases it doesn’t, and shouldn’t, work like that. For example, you don’t usually look for a light bulb first and then buy the lamp fixture. You search for the lamp fixture first, and then add the light bulb to complete the purchase.