Material Return transaction through the Manufacturing REST API for a non-tracked Inventory item

We are trying to create a Material Return transaction through the Manufacturing REST API for a non-tracked inventory item and split the returned quantity into multiple Line Details records because each split line has a different custom Reason Code.

The inventory item is NOT lot/serial tracked.

Expected Behavior

We want the Material Return transaction to create:

Main Line:

• Quantity = -3.00

Line Details / Allocations:

• Qty = 2.00 → ReasonCode = BALWOFF
• Qty = 1.00 → ReasonCode = CRWOFF

So the total allocated quantity should equal the document quantity (-3.00) without creating any additional allocation lines.

Current Problem

When we send the payload below, Acumatica creates:

• the two intended split lines
• PLUS an extra allocation line with quantity = 3.00

As a result:

• Total allocation quantity becomes incorrect
• An unwanted extra split line is created in Line Details

Screenshot attached for reference.

Current Payload

{
    "Hold": {
        "value": true
    },
    "Details": [
    {
        "ProductionNbr": {
            "value": "AM000280"
        },
        "OperationNbr": {
            "value": "0010"
        },
        "InventoryID": {
            "value": "MGRESVINLT"
        },
        "Warehouse": {
            "value": "WHOLESALE"
        },
        "Location": {
            "value": "R1S1"
        },
        "UOM": {
            "value": "EA"
        },
        "TranType": {
            "value": "RET"
        },
        "InvtMult": {
            "value": 1
        },
        "Quantity": {
            "value": -3.00
        },
        "Allocations": [
            {
                "Location": {
                    "value": "R1S1"
                },
                "UOM": {
                    "value": "EA"
                },
                "TranType": {
                    "value": "RET"
                },
                "InvtMult": {
                    "value": 1
                },
                "Quantity": {
                    "value": 2.00
                },
                "ReasonCode": {
                    "value": "BALWOFF"
                }
            },
            {
                "Location": {
                    "value": "R1S1"
                },
                "UOM": {
                    "value": "EA"
                },
                "TranType": {
                    "value": "RET"
                },
                "InvtMult": {
                    "value": 1
                },
                "Quantity": {
                    "value": 1.00
                },
                "ReasonCode": {
                    "value": "CRWOFF"
                }
            }
        ]
    }]
}

Observed Result

The transaction is created successfully, but Acumatica generates:

• Qty 3.00 (extra line)
• Qty 2.00 with ReasonCode BALWOFF
• Qty 1.00 with ReasonCode CRWOFF

The extra Qty 3.00 allocation line should NOT be created.

Questions

1. For non-tracked items, is there a specific way allocations should be sent through REST API to prevent Acumatica from auto-generating the parent allocation line?
2. Should allocation quantities for Material Return be sent as:
   • positive quantities
   • or negative quantities?
3. Is there any additional flag or field required to tell Acumatica that allocations are fully assigned?
4. Is using custom fields like ReasonCode on allocation splits causing Acumatica to generate the extra line automatically?
5. Is this expected behavior in Manufacturing Material Return transactions for non-tracked items?

Any guidance would be appreciated.