target field account modifier

in EBS, we want to differentate GL posting for trading partner, for example external transaction NTRF, trading partner 1234, we want to post to Dr: 12340000 Cr: bank

for trading partner 1235, we want Dr: 12350000 Cr: bank, how can this be done, in search string use, should I use EBVGINT(posting rule) or EBKFMOD( account modifier) or others? thanks