Add logic to forms eg only show email opt-in if previously no or blank

Hi Paul,

You can dynamically toggle visibility of form fields as explained here.

Hope this helps!

You could also consider enabling progressive profiling in conjunction with some field visibility rules to achieve all the functionality you need (i.e. to have  a field displayed for someone only if it is blank on their record, and not others).

In addition to visibility, is it possible to have certain fields only populated if the current value is blank for the lead? For example, a Lead Source is not a field you want constantly updated, but if a new lead is being created, you want the hidden fields to be populated based on the URL parameters.