The addition of the Contacts sub account has been great and very helpful, however there are a couple of tweaks that I think it could benefit from.
1) When the sub account logs in with their own credentials to submit a ticket, I think the ticket could make it more obvious that the it has come from the sub account. This would accommodate all those people who forget to sign their submissions(which happens quite often for me) and also make it much clearer on who said what if both the main client and sub account contact respond to the same ticket.
I was just thinking that where it displays the client's name, it could display it in some way similar to the example below:
on behalf of:
2) The other thing I noticed is that in the client's log section it does not display the sub contact's name when they have performed a task or modification to the account. Currently it just displays 'Sub-Account (number)'. This generic link makes it a bit of task to identify who has done something if you need to pass on that information to the main account holder, particularly if you have more than one additional contact.