risking it means if stopped by police she will be in trouble. 7 days must leave is the better option, or dont travel where you risk being checked and or change the flight and leave on the date the extension expires.
You mention her extension will expire ? You do understand on visa and visa exempt you can only extend once so if what you are saying she already extended once she can not do it again.
What visa is she on when arrival into Thailand and has she actually done one extension already ?
you do mean O visa on marriage, OA visa must be applied for outside of Thailand can not get it while in Thailand same as the OX visa is outside of thailand application only