Hello,

If we can add a final step in registration process to let people invite their colleagues or friends to join them by adding their names and emails in a very sleak way, no need to messages and text editor, just two cases : Name & email.

We use this in google forms when we create a poll, in last step we ask people if they want to invite someone.
We also use this as custom field to let members in the website add some email addresses until we invite them manually after.

please find an example of people invite feature which i find on another website just yesterday.