Debt schedule with existing bonds

i'm working on a model where the company has an existing $400 bond due 2022. It's not currently traded at par and was recorded in the balance sheet as ~$388 as of FYE2018.

Initially my debt schedule was simple - opening balance for 2019F was ~$388, no repayments in that year yet (bullet maturity only in 2022). When i reached 2022F, i simply deducted the ~$388. it's a simple model, where my cashflow from financing activities was calculated using the difference in debt between 2022F and 2021F - an outflow of $388 in this case. However, this technically isn't correct as the actual cash that goes out is actually $400 when the bond reaches maturity.

Should my debt schedule reflect the amortisation of the bond discount until the book value reached $400? i will then need to adjust the linkages to my cash flow statements to capture only the actual cash impact rather than simply change in debt. i guess what i'm really asking is whether there's an example of a good design of a debt schedule to account for bond discount/premium amortisations. Looked at some of the financial modelling video courses online and many seem to skim through debt schedules.