Write off of part of a foreign currency invoice

This is quite tedious. Also, when there is a small overpayment on a purchase invoice, it should be possible to write off the overpayment (in the same way as an underpayment).

Thank you for the idea Chris and thanks Alex for giving us more detail, I feel it's now far more clear. As with all ideas on Community, the more votes it receives the more likely our Developers are to consider it for implementation as that will mean it benefits a larger number.

Thanks

Chris