We have a registration form to create - if the number of people attending are 3 or less, the form can go to a thank you for registering page.  If the number of people attending is greater than three, I need to send them to a payment page.  I can't seem to find how to do that - hoping I'm just missing something.

Thanks in advance!

Form Master does not support Conditional Redirects.
I have had a few request for this in the past several months and will add it to the next minor release.
Unfortunately I am going on holiday this memorial day weekend here in the US so it may be up to two weeks.