you create a fields constant(value=1) field type is calculation.
then relate both by this field.
then in event details draw a portal that comes from the Independent contractors tables.
Just see what happens
Sound like you need a portal to a join table to list these records on your layout.
Event Details---<Event_Contractors>----Independent Contractors
Event Details::EventID = Event_Contractors::EventID
Independent Contractors::ContractorID = Event_Contractors::ContractorID
You can add fields to the Event_Contractors table to document the specific responsibilities that contractor will have at that event.
This is called a many to many relationship. Here's a demo file that links "contracts" to "companies" the same way I have described linking event details to contractors. Check out how the portals are set up with value list formatted fields for populating the join table with the correct data.