This toddler drives me CRAZY!?

First of all she doesn't HAVE to listen to you, you are not her mother, you're not even her step mother, you're only the woman who sleeps with her father. It is not HER fault she has never been taught discipline. She has TWO parents and obviously they have never disciplined her (discipline does not mean hitting). Either your boyfriend grows a set of balls and a backbone and starts disciplining his daughter or YOUR problem will definitely affect your relationship. Whether you feel comfortable or not you have no right to discipline this child anyway. You should have set the record straight before the two of you moved in together. Setting the record straight now is like shutting the barn door after the horses have all bolted Obviously you didn't know this guy well enough to move in with him since you had no idea how he treated his own child. That was a choice you made. It is totally up to you whether you tell him how you feel. That is a choice you will have to make and you will have to live with the consequences.

You need to have an open discussion about this. Do you expect him to also discipline your child?

You need to see if you have similar parenting styles. Do you both agree with spanking? What core values would you like to teach your children? You CAN NOT let his child walk all over you and if he is not going to be there every moment with her to discipline when she steps out of line, you will have to do it. Find out if you have the same parenting styles, talk about your hopes for your daughters, ideas you have about how you will discipline your children.

For example: I would like my children to grow up and be hard workers who can appreciate a job well done, who don't wine for what they don't have, but find out what they can get what they want - empowered. I want them to be open to all lifestyles and not judgmental of how others live their lives, I want them to know the value of a dollar and how to manage money. As children I expect them to do as they are told no matter which adult tells them to do it (same as you) I often tell my son 'listen first, questions later'. I expect them to share without complaining and to treat others as they would like to be treated.

If you can't agree on parenting styles then you will despise the different treatment that you see him giving his daughter over yours.

give it some time; try playing with both girls, i believe shes just going through a stage, tell him how you feel and maybe you guys can come to a conclusion on how to discipline each others kids without stepping out of line.

Of course she doesn't listen to you, your new. You have to talk to him about it, it won't get any better until you do. She sounds like shes being 2 in many ways though. How would you feel if he was acting like this towards your daughter? What would you want to happen if the places were reversed?