Beardo family

The Beardo Family was the name (or nickname given by Greg) to the main antagoinsts of. Greg encounters them at a cheap motel during the road trip; they had hogged the hot tub. Later at night, the children of the family got ahold of a washing cart and were ramming it into walls until Greg noticed and scolded them, this made them complain to their father who went to find him but went to the wrong door. Later, he finds them at the fair where he narrowly avoids getting face-to-face with them. At Soak Central water park, they stole the Heffley's seat and their stuff was piled on the ground.The family had put the key there but it wasn't there and they had lost it, so they went to the staff of the water park to get the locker open but it turned out it was open and was empty. They thought the Beardos stole it. Later, they found their van near a motel and their room open. They went inside and made use of the room since they thought it was their money since they stole their credit cards, but they later arrive, Greg and Rodrick run away while their father was in the bathroom, but the Beardos saw him, so he picked up their car keys, threw them into the bushes and ran back and drove away. Later, Greg finds out the key was in his shorts, so they might have not been the thieves.

Trivia

 * They may not have been the thieves since Greg later finds out the key was in his shorts, hence their belongings remained in the locker at the water park.
 * Since they were going to same places in their road-trip, it is likely they were also following Family Frolic