With the module Form Submission Update it is possible to refine a lead after the conversion So you can ask the most important questions first and ask more questions after the lead data has been transferred.
Before the normal form submission module must send the lead data for the first time.
The functionality to update the lead has to be implemented on your side of the endpoint. We transfer all old data plus the new data.
As identifier you can use the parameter uuid, which we set once for a user and store for 30 days in a cookie (tracking settings).
So if the user submits a lead again during this time, you can assign it using the uuid.
The Form Submission Update module has the same settings as the Form Submission Module. This way you can specify a different api endpoint for a lead update.