Is possible to update a existent Leads through a Webform ?

Is possible to update a existent Leads through a Webform ?

You have a ZOHO CRM integrated with your Website through a Webform that generate Leads.

Is possible to update a existent Leads through a Webform ? i.e. If you have a Lead in your Zoho CRM and this Lead go to your website and complete the webform (with the same email), is possible to Update this Lead in CRM?

I try without the Unic property of Email in the lead's Module: The result is Lead duplicated.
I test with Unic property of email: The result is that the Lead from webform is refused and no changes was made to the Lead in CRM.

Thank you very much.