To track consents in the GDPR logs using an existing checkbox, you can try to modify the code of the existing checkbox by doing some sort of integration with the dynamic checkbox feature.

The existing checkbox must be modified in order to include 2 special attributes:

Code:

data-role="gdpr_dynamic_privacy_policy_checkbox"

Code:

data-placeholder="{nameofyourchoice}"

to have a final resulting checkbox such as:

Code:

<input data-role="gdpr_dynamic_privacy_policy_checkbox" type="checkbox" data-placeholder="{nameofyourchoice}" value="1">

However, to make sure that all the necessary scripts are included in the pages, there must be at least one record in the dynamic checkbox list of the backend, even if it is not used anywhere.