Description
Use this filter to modify whether a user that is already subscribed to your list has their groups replaced when submitting the form a second time. By default, the original groups are kept and any new ones are added.
Usage
add_filter( 'gform_mailchimp_keep_existing_groups', '__return_false' );
You can also specify this per form by adding the form id after the hook name.
add_filter( 'gform_mailchimp_keep_existing_groups_1', '__return_false' );
Parameters
There are no parameters.
Examples
Replace existing groups.
This examples returns false so that the groups are replaced.
add_filter( 'gform_mailchimp_keep_existing_groups', '__return_false' );
Placement
This code can be used in the functions.php file of the active theme, a custom functions plugin, a custom add-on, or with a code snippets plugin.
See also the PHP section in this article: Where Do I Put This Code?
Source Code
This filter is located in class-gf-mailchimp.php.