There is a subtab named GL Impact in the cash sale transaction . Does anyone know how to add a line into this using suitescript 2 ?

https://docs.oracle.com/cloud/latest/netsuitecs_gs/NSCGL/NSCGL.pdf custom GL lines plugin

i want to add an account (from the chart of accounts list) in the GL Impact subtab of a cash sale of sales order in which a specific promotions is applied..

I suggest making a saved search that does it & adding it as a new sub tab

ok