How can I prepopulate the data on the new form?

I want to give users the choice of selecting pre populated data (Existing clients name and address) on a new submission form.

Hello,

Thank you for contacting us.

You can prepopulate the data to your JotForm via URL. Here is a guide helps to you: https://www.jotform.com/help/71-Prepopulating-Fields-to-Your-JotForm-via-URL-Parameters

Also, you can redirect the user to another form and prepopulate the second form with the previous form's data. Here is a guide about it: https://www.jotform.com/help/351-How-to-Automatically-Pass-Form-Data-to-Another-Form

Please check this guides. If you have any questions or issue, please do not hesitate to contact us.