I didn't fully understand your question. It depends on how do you want to utilize the form.
However, if you already have information about your contact, then you can auto-populate the Form Field via the query string for your known contacts. But you've to use the exact same internal name (name of form field) in your form & URL query string.
i'm creating a form that will allow person A to enter information about person B (who is not in our db), when Person A completes that form, they need to choose their name from a drop list of approved persons, before the form can be submitted. Person A is not a staff member nor are they logged into a website, therefore the form can't auto populate their information, they need to select their name from the list of approved persons.
I'm trying to work out how to make that "Person Submitting Form" field a drop list based on a field in our CRM.