How do I "extend" a collection?

Hi everyone!

I have two groups of people that I need to enter into a database. The first collection, let's call it attendees, has the following attributes: lastName, firstName, emailAdd, registrationDate. The second collection, let's call it volunteers, has the same attributes as that of the attendees collection but with additional attributes: committee, volunteerDate, contactNumber.

Can I simply "extend" the attendees collection, adding the new attributes to create the volunteers collection? If so, how? Or would it be better to just have a collection containing all the attributes and just have an additional atteibute to differentiate an attendee from a volunteer?

Thanks for your insights.