Foreign stock purchase with domestic currency trading commission

[Geoff]

I have read the gnucash documentation regarding a foreign currency stock transaction but was unable to find the following use case.

Section 10.4.2 — Purchasing foreign stocks — provides a good description of how to record foreign stock purchases but does not explain how to record a trading fee on the transaction. 

If the trading fee is also foreign currency denominated, everything works perfectly. However, in my case, I have an account that charges a domestic currency trading fee and here I seem to run into the problem that a single split can only seem to handle one currency.

If I force the purchase of the stock to a foreign currency then the commission is also recorded as foreign currency and changes through time as exchange rates move. What I need is that the commission remains fixed in the domestic currency.

Does anyone have any advice about how to record this transaction in a way that would preserve the ability to correctly show the commission in the “Advanced Portfolio” report ?

Thanks in advance