Accounting for multiple currencies held in a broker's cash wallets?

I’ve been running with PP for 3 months and I like what I see. I’m trying to reconcile transactions with one of my brokers and see I have not handled USD transactions and conversions for that broker well enough. My base currency is GBP.

I think I should add a USD Cash Account and record USD transactions conversions in that. But is that correct and what’s the best way to manage this?

Update:

When I posted I was not so experienced with PP and I can understand currency conversion and Buy/Sell transactions a little better. With the broker in question I paid in GBP and it delivered a number of shares (trading in USD). On selling these will deliver an amount in GBP.

Like any complex application, PP takes some getting used to.