How to turn on "do not allow duplicates" but do allow integration updates

In our line of work folks usually start our sales process by filling out a short interest form. When they are ready to enroll they follow up our interest form with a much more thorough application.

I'm curious if there is a way to use zoho forms to fill out more information in a lead profile that has already been created, that is, they already filled out our short interest form.

I've heard this can happen via zoho forms integration with the CRM when "do not allow duplicates " is turned on.

But what I'm finding is the "do not allow duplicates" simply blocks new forms coming in. It doesn't update old leads. The old information is kept. Any new or updated information from another form is discarded.

How do I make sure that the "do not allow duplicates" feature does allow profiles to be updated as we are collecting more information on a customer using the same email?