Total amount in GBP to be shown on invoices in case of foreign currency

Hi Support team and all,
Our company is changing now to be under VAT scope.
We have changed QuckFile accordingly, everything works fine except for one little issue.
The rule says if we issue an invoice in a foreign currency it is OK, but we have to show on the invoice the total amount and the total vat amount in GBP as well.
I tried to set this in the Invoice customisation area, however in the total section (Footer totals), it says:
"There aren't yet any available settings for the footer totals area." And on the invoice itself only the actual currency is shown, GBP is not there if I issue an invoice in EUR or USD for example.
According to the rules my accountant says that the converted GBP total amounts should be visible on every VAT invoices.
Is there a possibility to add this feature for the invoice customisation in Quick File?
Thank you
Zsolt Kelliar