The Beagle Brats are the nephews of the Duckburg Beagle Boys. Seemingly their moral compass is not well-defined at their current age, as they sometimes can be as criminal as their uncles, sometimes are just bratty, and sometimes they do downright legal work like shoe-shining, much to their uncles' chagrin.
Numerous similar young relations of the Beagle Boys appeared in the DuckTales episode "Take Me Out of the Ballgame". They were also referred to as the Beagle Brats, although it is not specified how they are related to the rest of the Beagle Boys.
The trio usually known as the Beagle Brats are a set of identical hellions who are the nephews of the three main Duckburg Beagle Boys. The Beagle Brats are a handful even for their equally-immoral parents, who often shift their guardianship to said main trio who, in turn, have no idea how to deal with them. The Brats seem to have a rivalry against the Junior Woodchucks, each seeing the others as their polar opposite.
Though the triplets 1, 2 and 3 are usually the ones referred to as the Beagle Brats, there is evidence that any children of Beagle Boys who follow the family traditions at an early age can be referred to as Beagle Brats.
the Beagle Boys appeared in the DuckTales episode "Take Me Out of the Ballgame", The Beagle Brats are child relatives of the Beagle Boys, and numerous of them, all unnamed, faces off against the Junior Woodchucks including Huey, Dewey and Louie, Doofus and Webby in a game of baseball. Coached by Ma Beagle, they are shown to share the Beagle family's fondness of foul play, although eventually they lose the game.