Still not sure I follow. If I make a payment on a credit card, it shows up as a transaction from asset checking account to the liability credit card. It shows up on both accounts already. When I later import OFX transaction files, it sees the payment in the OFX and matches it up to the existing transaction: https://lists.gnucash.org/docs/C/gnucash-guide/importing-fro...
Apparently not all import assistants do this for some reason.