lichengkun135 this extension doesn't allow users to invite other users. It wouldn't make any sense for groups unless you also had an extension that let users create their own groups.
Maybe that's a feature you would like to see in the FoF Doorman extension as part of registration invitation (not group invitation)?
Either way it's definitely something I can do as a sponsored extension. It would likely be a new extension though, I see no benefit in modifying this present extension that has a different use case.
