Hi Mark,
If you are implementing/using Ariba On-premise then your implementations/development team can develop/customize the above requirements accordingly. Though in case of On-Demand implementation, you will have to check with your respective Ariba support/technical team, who are setting up the realm for you, the feasibility of above customization.
I believe in On-Demand there are minimal chances that Ariba would be customizing such requirements. However you can check with them.
Thanks,
Sandeep Jain