The system really needs to implement a quality control system that allows version control (history and footprints) for each user to be documented similar to the below image however i would push for this to be developed further. Accountright has a similar view than Xero's as per below but less information provided and also doesn't allow for any changes made to these invoices and quotes to be viewed along the way.
If a staff member has made changes to an invoice, i want to see it. I also want to be able to view the version of what has been changed. We've had a number of instances where a quote has been changed by a staff member as per the clients request however another staff member may come in and have no idea what has been changed.
"Version Control for quotes and invoices"