Has anyone used 123 magic with their children and had success?

My almost 3 year old has become tyrannical lately and I am at my wit ends. Naughty corner is not working, taking her toys away does not work. She is flately refusing to go to the toilet and was training successfully. I can not leave her alone with her younger sister atm she is so nasty towards her. I know she is suffering bit from jealousy with her sister but all the other stuff with it and not working is becoming too much. I am on my own with my DD’s 6 days a week and I need to regain control before I turn my DD into a spoilt out of control brat that is horrible.

I’ve seen 123 in action, but I MUCH prefer Jane Nelsen’s Positive Discipline approach. The a-z book is a very easy format as well.

And good luck! It’s hard with a new little one and a toddler, especially with very little help.