Expanding Salesforce Community for Customer Advocacy and Support

Hi all! We currently have a community ran by our support group that is available for our customers that pay for maintenance. Although this includes most customers, there is an additional line item that is needed to have access. Support advertises this as a customer response system and customers can log cases directly in the community and also post in forums looking for assistance. The community is through Salesforce. We don't have any other community currently, but I would love to have something for our advocates and the broader customer base. Has anyone had multiple communities or an existing support community that you expanded into something more? We have explored creating a separate group within the Salesforce community, but curious if anyone has experience with this.