You won't like the answer
According to UA CSRs you are allowed to take only one person into E+ with you. If there are more people than that in your party, you may either split up (they will even let all of the kids sit together in the back of the plane!!!), fork over the extra money for everyone to sit in E+, or sit in the back together.
I personally would LOVE to let the 11, 10 and 8 year old sit in the back by themselves while I sit in E+ on our upcoming 8+ hour flight, but I don't have the guts to do it.