i made some discount to customer, principle quite the same.

so we make some customize(for accounting), but basic is working.

so payment term-percentage 90% in 30 days. and balance in i dont know 60 days.

so accounting entry will be splitted in 90 and 10%. so in reconciliation you can create write off model.

o for invoice some improvements and you can show 90% amount and due date and all amount.