Your question wasn't about what sort of person the mum is though.
my question to you would be what sort of person allows their 3 year old to be "sent out" to them (i presume he sits in his warm car while the 3 year old comes from the house?) if the mum comes with her to the car, why dosen't your brother just say "where is her shoes and coat, luv?" Why is your bro not man enough to actually pick her up from the door and ask the same question, or say "can i have some extra clothes please"?? Seriously if HE can't sort it out, how can we?
My other question to you is why do you NEVER say thanks for all the replies you get to your questions? (personally i think it's because "thanks" would be quite final,and deny you the opportunity to spin the thread out for days and days)