How old are your kids and how bad is it?

DD is almost 4 and DS is 15 months. DD has been acting out against us - being defiant, screaming and crying, with "i want a hug!!!!!" alternating in between. It's constant emotional whiplash. It also comes without warning. DS' jealousy is a little funny as he will push DD out of the way if i'm giving her a hug, but it definitely doesn't help the situation and i end up with 2 crying kids.

I have been really good at remaining calm, but sometimes when it's been hours of this behaviour, i'll show flashes of annoyance and impatience. I want her to be able to release her emotions, but at the same time i don't want to spoil her and think that her bad behaviour is acceptable.

Anyone else dealing with this? I found some helpful links last night that gave me some perspective.

http://www.ahaparenting.com/ask-the-doctor-1/preschooler-jealous-of-baby-developing-attitude

https://www.washingtonpost.com/lifestyle/on-parenting/big-sister-having-trantrums/2014/12/09/654d39c0-7be7-11e4-84d4-7c896b90abdc_story.html

http://www.ahaparenting.com/ask-the-doctor-1/4-year-old-whiny-defiant-mean-to-baby