Rather than being restricted to store files only in Dropbox allow us to create link to file anywhere either on Internet or locally

We want to store files with purchases but we o not want to use Dropbox. We would like the ability to either..

Create a 'link' to a file resource either via http:// or file://

or

Have the notes field recognise valid URI's thereby giving us a way to reference an online resource and click on it. This would open in a new browser window displaying the target of the click. That might be a file we have stored in OneDrive, SharePoint or elsewhere or it might be a web page related to the purchase.