Hello. I have a just turned 5 year old and I know that at 4, they are able to understand "no" and "why". I think you are just going to have to be the strong one and tell her that it is going to ruin her teeth, it is just for babies, and mommy and daddy are taking it away on ????? date. You have # more days and it is gone. In the trash. Put that stinging nail polish on her thumb, not just on the nail, all over it. Unfortunately you have waited too long and it is a habit. They say to rid those things by one so they don't form a long term habit....it is hard to do. We always give our children a deadline, we build them up to it, for example, when we wanted to potty train our son, we told him that he has one month left of diapers. On his 3rd bday they go in the trash. At the last week we counted down the days to him. On his bday he got up, threw them in the trash and that was that. Make it something that makes her feel like a big girl, talk her through it. When you do it, don't keep them around so that you can be weak when she cries. Throw them away, neither one of you can give in. She will cry and you will deal with it. It won't last long and if it does, you go from there figuring out something new. Depends how strong willed she is. I am a strong believer in trying to do things the nice way but if all else fails, we are the parents and that is the end of it, "you are too old for the paci and it is time to give it up".............or, if you need a different option....you take her to the hospital to visit the new babies, bring ALL her pacifiers in a baggie. Tell her that you are going to leave her paci's with the new babies that REALLY need them. Then, when you leave, hand them to a nice nurse and tell her that you are leaving them for the new babie's (wink, wink) and then she can throw them away. Or, you can mail them to the paci fairy........she takes it to the mailbox and have it addressed to a friend, family member, neighbor, and they throw them away. Tell her the paci fairy brings them to new babies, that is how she got hers.
Good luck,
W. M