We are trying to rewrite integration with Mailchimp by using API v3.0
In v2.0 they have method for adding members to static segments (https://apidocs.mailchimp.com/api/2.0/lists/static-segment-members-add.php)
Can't find this method in new API or some sort of replacement. Possible solution might be creation of new segment each time when new campaign started, but also can't find request sample for this.
If you have other ideas for workaround, please suggest. Any help is greatly appreciated.