Avoid accumulation of a sub transaction to main 0100 sub 0020 in Billing &

Hi

We need to create a new sub transaction in the billing process (main transaction 0100).

There is a new legal demand to run different interest for a special "drought tax". The calculation is included in the billing schema. Therefore we need to avoid accumulation of the new sub transaction to sub transaction 0020 in Billing & Invoicing processes.

.

How can we cause the new sub transaction to take place as a separate line item in the FI-CA invoice (in customer financial card TR. FPL9)?

Thanks

Shosh