How to update Inventory LOT DFF and Locator through same FBDI?

Hai,
We are trying to do subinventory transaction through FBDI, to update the locator of a LOT and one of the LOT DFF attribute. Locator is getting updated, but the LOT DFF is not getting updated.

To update this we found one 2 APIs, but we need to make two separate API calls to update this field for each barcode: one to retrieve the unique lot identifier, and another to update the custom flex field (sequence). This becomes highly inefficient when dealing with thousands of lots, as it doubles the number of API calls required. We expect at a time around 50K+ lots will be update through this FBDI. So calling 2 APIs calls feels not ideal.