We have a client who use Form Assembly forms (non-Marketo forms) to submit Contacts in SFDC and update data across custom objects.
What we are looking to do is set up their forms to capture the Munchkin Cookie ID into a hidden field and pass this through with their record into SFDC, so when they sync into Marketo we have their cookie ID.
What API functions should we be using if we want to use the Munchkin ID value to look up to see if there is an Anonymous lead with that same ID, and merge the two records together?