I've been reading through the various feature requests and did not see any that address this specific need.
I would like to be able to create a loan account (manually, as it is not attached to a bank, but rather a family member) and show the starting balance of the loan, the APR, monthly payment plan, ability to modify payments on a monthly basis or larger grouping, denote extra payments. In the end, I would like very clear visibility on the progress of paying a personal loan off.
It would be extremely helpful if the debits from my checking account could be identified and subtracted from the balance of the loan account.