Please Note: The Groups addon is a 3rd party solution and was not developed by the MemberMouse product team. As such the MemberMouse customer success team cannot offer assistance or guidance in using the Groups addon. The Groups addon is opensource so feel free to contribute any enhancements you'd like.
With the Groups addon you can define different types of groups allowing customers to create their own group with a predefined number of seats and use a signup link so members can join their group. This makes it so that a single customer can pay for multiple seats and then members can join their group for free or for a price based on how you configure the group type. In order to use the groups extension plugin MemberMouse must be installed and activated.
You can download the plugin here: http://github.com/membermouse/membermouse-groups-addon
Note: the plugin directory under /wp-content/plugins must be named MemberMouseGroupAddon in order for the plugin to function properly. The current download from GitHub installs it in a directory named membermouse-groups-addon-master. You will need to rename that directory after uploading the plugin and prior to activation. This can be done via cPanel or FTP.