Hi Cjoseph!
I've already set it up so sponsors have to authorise the guests after registering (by way of clicking the email link, going to clearpass etc).
The challange in this case, is that the customer wants anybody within the business (identified by way of the sponsor email domain) to be able to "authorise" guest registrations. I've already sorted that part by way of the validator argument (in that the sponsor has to be in @customerdomain.com).
In addition, he didn't want the sponsors to have to "login" to do it, as it's too complex for them (most are um, "low skilled"). I think that rules out your suggestion?
With that in mind, he just didn't want a single member of staff (within the domain) sponsoring themselves and abusing the system as it's really only intended for real guests. People could still get around it of course by teaming up, but by doing so they have to be vocal with one another about what they're up to. So, it's different if you get my drift?