If you schedule meetings on behalf of other people, using your own PIN isn't always an option, especially if you're scheduling multiple meetings for the same time.
The person who will be scheduling the meetings (i.e. the EA) on behalf of someone else (i.e. the Executive) will need to be given permission to do so, by your company's Biba organization admin. Request that you be given delegate privileges.
Once you've been set up as a Delegated Scheduler, both you and the person you will be scheduling meetings for will receive an email alerting of the new permissions.
Your email will contain all the information you need to set up a meeting on another user's behalf. It's just like scheduling a regular Biba meeting, but you're inviting one extra "Biba user".
Note that delegates can only schedule meetings using the other user's Personal Meeting ID.
If you're using Outlook, the Outlook plugin for Biba makes it super easy to choose which calendar you're setting the meeting up on by allowing you to select from a pick list. You can be set up to delegate on multiple calendars.