Prorate discount by AR Invoice Lines to a specific Discout Account

We want to proroate /allocate discount by Invoice Lines Amount on AR Invoice. Also we want to do it by specific freight account. I am enable to allocate freight as -ve revenue account to Invoice lines by using Receivable Activity that uses type 'adjustment' and 'GL account account source 'Revenue on Invioce'. My question is how to prorate based on invoice lines amounts to a specific 'freight account'

e.g. we have account segment 'Product' on our sale account.

so assuming AR invoice was created with two lines as follows

Revenue -Product A: 100

Revenue - Product B: 200

At receipt application a discount of $30 was applied. We need the following account to be created  using freight account 5010