EveK's suggestions exactly as she made them would work perfectly and need to be implemented as soon as possible. Error messages need to specify what the problem is and with whom. And a simple Yes/No dialog needs to pop up if a person will be advancing their Coil past their current point when the duty is registered by the party leader.

Something more sophisticated would be better long term, so people don't have to all gather in Wineport just to find out something is wrong and then potentially have to start all over again. Ultimately, I think the Coil needs to be adjusted to make better use of the duty-finder. Requiring groups to pre-form is very sensible for the Coil. But I think allowing groups to form and then apply to the Duty Finder like most people do with Titan HM would be a big improvement. It just needs to handle the complexity of the Coil's presently unique progression system and have protections for the same issues we are having here.