ES, I suspect that this is all part and parcel of your husband making his little girl a princess, allowing her to run the household, and pitting him and her against you. I really do feel that you two need family counseling. If you don't get help with this issue, I'm really afraid your marriage is going to be very difficult in the upcoming years, AND that your daughter will end up treating YOU very poorly in her tween and teen years. And her dad will always stand up on her side. She will end up expecting every man in her life to treat her like her daddy does, and regular men will not only be unwilling to do this, but unable. What your husband doesn't understand that he is setting the stage for, is that she won't be able to have a good relationship with a boyfriend or husband.
Please get him to a counselor, a MALE counselor, so that he will listen. Go yourself at first so you feel comfortable with him. Then bring your husband. If your doctor is aware of the scripting problem and how your husband is doting on her with it, allowing her to tell you both what to do in your home, then the ped should know some good counselors to send you to in order to get help...
This is about SO much more than birthday cakes and half-birthdays...