Firstly welcome to the forum.
Ask your brother to join this forum and im sure we could educate him on walking a dog on a lead near a busy road.
I would seriously consider not allowing him to walk the dog. Maybe have a quiet word with your mum and plan to walk him between the 2 of you, depending on your daily routines.
What breed of dog do you have?
Owning and the daily care of a dog is not about fitting in. People do it because they love the dog and have made a choice to take the responsability.
Same with any pet.

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georges mummy