Form Validation using Custom Thread Fields

[ZiNgA BuRgA]

XThreads can't do conditional inputs, only outputs, so you'll need to use conditionals to check if it's Yes/No when displaying, rather than it being posted.  Alternatively, use one field and use Javascript to put in the Yes/No button rather than a threadfield.  Basically, add something like (Not attending) to the number of guests list.

Note that Javascript can't exactly enforce it since users can simply disable it.