2 year tantrums and immediately laughs after getting what he wants

Hi parents,Posting on behalf of my SIL as she’s about to lose it and I couldn’t advise on her situation as my kids are 4 years apart.My SIL has two sons (a 23 months and the other is 4 weeks old)The older sibling is going through a terrible time accepting his newborn sibling, it’s been a nightmare from day one.The mom resorted to hiring a live-in nanny to take care of the newborn 24/7. She rarely holds the newborn for fear of the toddler’s tantrum. She thought this would solve the toddler’s jealousy of the newborn.But even when the newborn isn’t there, the toddler would cry with tears and throws his body on the floor until he gets what he wants; ie his mom’s phone or his dad’s, candies, his brother’s pacifier, and just anything he has his eyes on. A simple “no” sets him off.As soon as the parent gives him what he wants, he immediately smiles and laughs happily. Like nothing had happened before and it’s like this all day everyday.My SIL is a doctor and said that because the toddler is crying with tears, it’s genuine distress. That what he wants must be given as he’s handling jealousy plus the terrible twos phase.How would you handle the toddler’s tantrum? Any advice is appreciated. Thank you. via /r/Parenting https://ift.tt/2uSjH27