Maximum number of (co)authors and change the presenting author

Via the abstract module -> Abstract dashboard -> Module settings you can set the maximum number of authors, co-authors and presenters.

You can also have the contact person start as a main author. 
When the contact person gets to the screen to add his personal info, he/she is automatically a main author. He/she can of course switch off the 'main author' option.

You can give your authors permission to change the presenting author(s) after they have submitted their abstracts. Simply enable the 'Allow Change Presenting Authors' option in the 'Abstract Module Settings' and your authors will now see their presenting authors listed in the 'Abstract Overview Page', where they can click on the edit icon to change their presenting authors.