If the expense is a business expense (as in, it will affect your profit), then entering it as a purchase invoice would be the best way forward, as @FolkLondon suggests.
You certainly can add multiple documents to a purchase invoice (I believe there’s a limit of 5 per invoice), so it creates an easy to manage log too. You could even link it up with Dropbox or set up the email feature on your account to make it a bit quicker too.
I’ve included two guides relating to this, which may help: