How do I count guests as main registrants?

I created an event form allowing people to register guests. I have a capacity of 50 people (including guests) How do I include guests on my total count or total submissions. 

The easiest thing to do would be to use one of our widgets that allow for limiting the number of times an option can be selected.  Since you will be allowing a quantity to be selected (main registrant + guests) I would recommend using a quantity gift registry widget or and inventory widget:

http://widgets.jotform.com/widget/inventory 

http://widgets.jotform.com/widget/quantity_gift_registry

That way you can limit the total quantity available to 50 instead of depending on the submission count.