We have a use case where we want to track which accounts in SFDC have signed up for one of our events.
A third party that manages the event passes us the Person data with a field like Event = "MA19" which indicates that they signed up for this year's event.
Based on that data I want to create a custom object record on the account that that person belongs to in SFDC.
For instance, Jon Smith from ABC Corp comes in and I create a custom object record (via a program/smart campaign) in SFDC.
How do I then stop a creation of a second custom object record if I get someone else from ABC Corp that signs-up?