Updating existing line items via BAPI_SAG_CHANGE

Hi Experts,

We are trying to update specific line items of scheduling agreement using BAPI_SAG_CHANGE.

Although we are passing specific line item, BAPI is considering all the line items under agreement and throwing an error for the item which we are not passing as an input.

Please help what is the correct way to update existing line item via this BAPI?

Regards,

Sanjana