> ## Documentation Index
> Fetch the complete documentation index at: https://developer.jtl-software.com/llms.txt
> Use this file to discover all available pages before exploring further.

# AddReturnLineItem

> Adds a new line item to an existing return. On an installation connected to the fulfillment network, a line item that agrees with an existing one of the same return on delivery note position, state, condition, reason and comments is merged into that one instead, with the summed quantity; the response then addresses the surviving position.

If a request with this mutation's Idempotency-Key was already completed, the response's `extensions` contains an `idempotency.{responseName}` entry with `wasReplayed: true`.



**mutation** `AddReturnLineItem(request: AddReturnLineItemCommandRequestInput!): AddReturnLineItemCommandResponse!`

## Arguments

**`request`**: `AddReturnLineItemCommandRequestInput!` (required)

## Returns

`AddReturnLineItemCommandResponse!`

**`returnLineItemId`**: `ID!`

The ID of the newly added line item.