Problem

Cannot save Composite Item due to error: "Composite item cannot be part of other composition"

Reason

Linnworks only supports one-layered compositions. A Parent item can have child items, but those child items cannot have their child item.

Our system is not designed to support such setup. It is not possible to add composite parent item to another composite as a child as this will have a detrimental effect on database performance.

Solution

Instead, you could use another way of creating them. 

For example, there is a Composition1 which consists of 2 SKUs - SKU1 and SKU2.

If you need to create another composition Composition2 which should consist of Composition1 and SKU3, instead of trying to add it as  Composition2 = Composition1 + SKU3     you can add it as    Composition2 = SKU1 + SKU2 + SKU3

With such a setup everything will be counted correctly.

To see which Compositions you already have you can use one of the Query Data reports > Composite Export (Exports a list of the composite parent-child relationships, can be found in Dashboards > Query Data)