You should be one of the first ones on the plane because you have a child that is only 6 years old. Your whole family will be able to board together, You shouldn't have a problem as long as you will be on a flight that starts in the city you are flying from. If you are catching an connecting flight that passes through your city chances are there should be people already on your plane when you board. You still most likely shouldn't be a problem. Just ask kindly to people in the plane to move around for you, somebody will move most likely.
Those with medical issues are boarded first, then the A group. Those families with children under 4 are allowed to board in between the A group and the B goup. Then the B group boards, and finally the C group.
If she passes out from being nervous I would suggest that you attempt to get a pre-boarding sleeve so you can settle in first thing. A man flying on my flight just this week pre-boarded for this exact problem. He was the first on the plane, took his tranquilizers to calm himself for the flight and zoned out the whole time. He was the first person off the plane too as he sat himself at the bulkhead and was standing at the door waiting for the FA's to open it.
So might be worth the try to see if that would work for your DD.
HTH!
Lots of people get very nervous when flying...I doubt that alone is enough to get a medical preboard pass.
Here's the deal...
Get online at the 24 hr mark. When that screen comes up, with everyone's names on it, be sure to check everyone's name off...otherwise you'll have to enter each one on it's own. And that is going to be an issue for you.
As soon as you are good to go, at that exact 24 hr mark, and you have all the names on the conf checked off, you can hit submit. That should get you all checked in, in an early boarding group.
Will you get to sit together? Yes. Of this I have no doubt. Even those at the end of the B boarding group can find two seats together. It may be that you have to sit with one child, while your dh sits with another, but no child is going to be seated by themselves. I have seen even those in the early C group get some seats together so that mom and her young child could sit together.
It really shouldn't be an issue.