Do you have a "3rd" child?

I am the 3rd child. Granted I am a twin and my sister is just a few minutes older than me, but still was treated like "the baby" for the years separating my brother and I.
I can only guess this is what my mom was referring to when she said, "just wait until you have children of your own".
Being a stay at home mom of 5 isn't that challenging for me most of the time but there are bumps and sometimes potholes I find it hard to crawl out of once in :D

Right now my challenge is as you may have guessed my "3" child. I use it as an expletive most times these days.
Like me, she can do nothing for herself. For example: I asked her to put something in her room and she asks me to carry it for her. Then she gets to her door and tells me to open it. I tell her to open the door and she starts crying inconsolably until someone else opens the door. When I prevent them from helping her she puts her hand on the knob and hits it lightly, still crying.
She is also the kind of girl that when a crayon rolls just out of reach instead of raising herself up off her tush to grab it she screams in a Banshee sort of way not even saying anything about the said crayon  but waiting for one of her sisters to see her dilemma and do it for her.
I am sorry to say that was also me.
I remember wanting to swing on the best swing in Preschool and instead of waiting my turn I relied on my twins protectiveness of me, she would bully whoever was on the swing off and then stand there keeping everyone away from me while I spent the entire time being spoiled by getting the entire time on the best swing.

Now I know better and am unsure of where to go from here. I realize the mistake but how to correct it and save my "3" child from helplessness.
My 2 year old will happily dress himself when asked but my 3 year old will stand there with her arms up in the air and wait for some else to dress her. Her sisters are all to willing to do whatever she wants because her scream would curdle milk, and it gets SO old.
This royal pain that expects her servants to do her bidding is finding herself in timeout more and more. I even was so desperate to consult our pediatrician about this behavior. He laughed and told me that as long as she is safe to just remove her from the environment until she can be rational. That may be years from now.

One of the funniest and most frustrating thing is her language right now. 
We were trying to have her screened for Preschool and in order to do so she had to have some testing done. She meowed at the teacher for every answer, not once but twice!
Instead of using her words she just screams. Talk about frustrating!
But when she really wants to make her point she is clear as a bell! Using the right language and manners and everything, that little girl is sneaky!

*SIGH*


The rein of the 3rd child is far from over, let's just hope we all live to see the end!