Multi currency - One customer various currencies

In “Multi currency” situations, I have noted that a “Customer” can only be linked to one currency, which means I have to create 3 identical “Customers” if I need to invoice the same customer in 3 different currencies. Not a major issue, but it would be much “cleaner” if I could select currency for each invoice rather than have it permanently fixed for a Customer. (Actually the very same situation also applies to “Suppliers”….)

Yes, most from accounting softwares are using same possibility.
Just create additional customers with the same name and at the end add currency type. Example Customer (USD), Customer (TRY) and Customer (EGP). By the default currency leave it just Customer. Then you will have all this “Customers” together by the reports.
Of course it would be more comfortable to have just only one but … i think it’s just some development issue.

If you are charging customer in 3 different currencies, then how much they really owe you? 1,000 GBP + 2,000 EUR + 3,000 USD? You have to maintain what they owe you in currency they’ve been invoiced until they pay.

Technically speaking, the tab shouldn’t be called Customers, it should be called Customer accounts but that would look silly to most people.

It’s common to maintain multiple customer accounts for one logical customer. Especially if each account needs to be denominated in different currency.