Jealousy! Momma Kitty Needs Help

Hi! Mommy Kitty Here.
I need help from anyone out there in the wonderful cat blogosphere.
Almost 11 months ago, baby Nate was added to our family.
That is enough time for kitty adjustment, right?
Well...if anything, my little Megs jealousy is just getting worse and worse by the day.
She isn't aggressive or anything towards Nate. (She pretty much ignores him)
But, she has been taking our her crankiness on her poor kitty brother, Jack. Jack is enough of a scardy cat, he doesn't need the added stress of a cranky sister.
I try and try to go out of my way on a daily basis to give Meg some extra attention. I know she is a kitty that NEEDS attention.
She naps on my lap for hours in the evening...and sleeps with me at night, but for her, apparently that is not enough.
She has taken to smacking up poor Jackie at night when he tries to sleep on the bed with us. (Sleeping arrangements are exactly the same as they always have been. She just decided it's HER bed)

Any advice on how to tone down Megs pissitude?
I love my baby cats, and don't want either one of them upset. I hate that Meg is feeling umm..neglected? and that Jack is living under the stress of being attacked.