What is going to happen once the configuration is completed... in all the postings to vendor or customer (you have defined the trading partners in master data) the trading partner field will automatically be populated for receivables or payables entry and the offsetting account entry.
This will also eliminate the need of creating the separate general ledger account to represent transaction relating to each affiliated company.
Trading partner setup will eliminate the receivables, payables, revenue and cost between affiliated companies. Means you difference of debits and credits or a net balance at a given point.
Thanks
Naseem