We are using a substitution created through transaction GGB1. This substitution is triggered at line item level of the accounting document.
As this is a FI-SL substitution, we cannot use the C_EXIT_PARAM_CLASS attribute to define the user FORM in the program ZGGBS000 (copied from RGGBS000).
While using tcode FB01, the substitution gets triggered properly. However, only the BKPF structure is available and fields of the BSEG structure are initial.
We want to fetch some information from the table KNKK and put those values in BKPF structure. But the customer number field is neither available in the structure BKPF nor BSEG. This is making it impossible to get the data entered by the user in the screen.
We have also tried fetching the information entered by the user in the screen by using function module DYNP_VALUES_READ. This works well for a couple of transactions. But as the AR posting can be triggered using many transactions (which counts to 15+, some of them background) this method is not practical.
Has anyone faced a similar challenge for applying substitution rules in FI-SL?
Helpful suggestions/workarounds will be awarded.