It's All Relative - Season 1 Episode 8 Road Trippin'

In an effort to get their families to join in the celebration of their upcoming wedding, Bobby and Liz convince their folks that the other's family is throwing an engagement party. Instead of working together, the families get competitive and try to outdo each other – which causes Liz and Bobby to flee to Vermont in frustration. Afraid that the young couple has eloped, the parents embark on a road trip to stop them – but a road trip with Mace and Philip is anything but a smooth ride.