I am creating an online customer form. My customers have a company name and Name/ID ("entityid") number that is unique to each customer. I have created this form to collect information about my current customers however when I submit the form a new lead is created instead of updating the current customer. When creating the form I see a disclaimer which states :
"When contact first name and contact last name fields are added to the form, the system will first try to find an existing record for the contact before creating a new record."

Here is the problem I am trying to update a