Yes, it is possible, but you could find her facing a ten year bar for Immigrations fraud.
It's only fraud if she lies to an officer when entering or when getting the visa.
But if she is truthful about her intention to apply to immigrate after marrying when entering, she will likely be denied entry. So hopefully she is not asked.
Please be careful about your advice - they could find thermselves facing a ten year bar for Immigrations fraud even so. What matters is what THEY perceive as intent. Fighting it out in court is NOT a good thing.