CiviEvent and Attendee Guests

[katesneed]

I am working on an event page and would like to be able to register a participant and identify their guests. I want to add the guests as new contacts but I might not have all the right information when registering so I need some way to add them as a guest of an existing contact but then add them as a new contact at a later date. Any suggestions on how to make this possible. If I have an event registration page, people can do it from the front end, but how can I do it from the back end?

Thoughts, suggestions or best practices please!