How to Make Adjustments to the AR Invoice at Line level for DOO orders

Use case:

A DOO invoice is created for ₹10,000 covering 2 items. An adjustment at Invoice level with adjustment type as line-level for ₹1,000 is applied to the invoice.

Later, an RMA is created for 1 item with a list price of ₹1,000.

The expectation is that the line-level adjustment should be distributed proportionally across Both items (₹500 per item). Therefore, when the RMA credit memo is generated, it should account for the proportional adjustment and create a credit of ₹4500 (₹5000 − ₹500) instead of the full ₹5,000.

However, the system currently creates the credit memo for the full ₹5,000. Why is the proportional line-level adjustment not applied to the RMA credit memo, and how can this behavior be corrected?