You can add a new form field to a form at any time. To do this, click on View All in the Forms section in Admin Home. Then click on Edit next to the relevant form.
Click here for details on creating the consent form field.
Will the Members automatically be asked to consent?
This depends on how you are using the form.
Membership Form
Once a member has completed a membership form, they will not normally be asked to review/update the form data, unless there is a new required field that they have not completed.
If your new form field is a required field, then the next time the member goes through checkout, they will automatically be represented with their membership form. They will not be able to go past the form without completing the required field.
If your new form field is not a required field, but you want the member to be re-presented with the membership form, then you may want to add another field which is required. This could be a checkbox with wording like this:
"I confirm that I have reviewed, and updated my form" or
"I confirm that I have reviewed the new GDPR Consent option above"
If you want to ask the members to login and review/consent to a new form field on a membership form, see here for details on how to email them with the correct link.
Subscription Form
When a member manually renews a subscription, they will be presented with their subscription form, pre-filled with the data that they have previously completed. If the subscription auto-renews, the member will not be asked to review/update the subscription form.
If you want to ask the members to login and review/consent to a new form field on a subscription form, see here for details on how to email them with the correct link.
Event Form
If you add a form field to an event form, then any member who places an order for an event that uses the form will be presented with a version of the form including the new form field.
If you want to ask the members to login and review/consent to the new form field on an event form that they have previously completed, see here for details on how to email them with the correct link.