So it took a while but we finally got a brief amount of time to play!
The three High Elves: Legolas- former soldier (my 7yr old son), Elsa- lost snow queen/princess...(4yr old daughter), Jackie- an explorer (10yr old daughter). The use of one cantrip was the major seller here.
I really wanted to have them learn the "real" rules of the game (we've played dumbed down d&d in the past) and they literally had no problem. For the most part, I simply just explained what skill to roll for if they wanted to do something that required it. To be honest, I thought I would have to really hold their hands, but to my pleasant surprise, it went off without a hitch! Even with my 4 year old...
Each had their own interesting background (you can read in the OP) and to set everything up I told them that they all happened to individually arrive in Neverwinter around the same time. Each was pretty much down on their luck. Their adventures so far haven't really progressed as individuals and that each was in the same frame of mind that they would 1) like to find some allies to aid them and 2) they were all pretty low on money and looking for a way to find some cash. I said they all met at the same Inn, found a common bond (all being High Elves helped) and became fast friends, and along comes Gundren Rockseeker looking for some adventurous folks for an easy task and some relatively easy money. (I basically didn't allow them to roleplay any of this, as we were short on time and I knew they would respond quickly to action)
So Gundren offered them the job and off they took the wagon on down Phandalin way. Jackie driving the wagon with Elsa seated beside her and Legolas walking along as a lookout. When they came to the ambush site, Jackie was ready to drive the wagon right on to the horses, but Legolas (with a high roll) spotted a goblin off to the side. He asked if he could sneak around and I ruled he could as long as he made the rolls, which he did.
It was here where I needed to explain to the kids that they should remember that their characters in the game wouldn't know information unless it is revealed to them in game. So when Legolas shot off to the right without a word, I had to remind the girls, that even though he spotted a goblin, their characters wouldn't have known that unless he told them what he saw. We could have replayed it, but I wanted something like that to show them that their characters should interact in game. As it is, the girls saw their companion dart off to stealthily to a thicket which slowed their wagon a bit. Then all of a sudden they saw a fiery
whoosh in the thicket and a burning goblin run out and drop dead. So we rolled for initiative.
The goblins got the drop. One ran from the bushes toward the wagon (and away from the fire) wielding a sword while two goblins on the other side shot arrows at the driver. The goblin with the sword attacked Elsa who was up in the wagon. On account of this I ruled that he would be attacking with a disadvantage, but he hit anyway for 3hp. One archer goblin missed and the other rolled a 1, so I said as he drew his bow the string snapped. Elsa dispatched the goblin at the wagon with her rapier and Jackie pinned the unfortunately unarmed goblin to a tree (1hp left). Again the second archer missed. The pinned goblin, with a last ditch effort yanked the arrow, grabbed a sword and ran for the wagon. Meanwhile Legolas took aim at the other archer goblin and roasted him within 1hp. Inspired at this Elsa to frost the little bugger running towards them and she did so with success. Now the recently roasted goblin archer wanted no part of this and took off back towards the Hideout.
The kids then investigated the horses and realized it must have been Gundren (they figured this out faster than my normal gaming group of 30/40 year olds...wha?). The explorer found the tracks and impressed grass that indicated bodies were drug and before I could give any more information she said, "Oh! Those goblins took Gundren and his friend. I'm going to go after them!". Legolas brought up his concern for the wagon and wanted to know if they could stash it off the road and cover it with leaves and branches and "make it look all broken so no one will take it".
Now I used the same scenario I did with my other group, in that the goblin who got away actually get's caught in one of their own traps. The adventurers discover the goblin hanging upsided down by one leg, very perturbed with himself and his bad memory.
Instantly Legolas intimidates him and reminds him that he is the one who blasted him with fire and he can do it again. Says he'll cut him down if he shows them the way to the hideout. Even said he'll pay him some money for his help. The explorer wasn't so trusting and wasn't so easy to part with their meager funds.
And then we had to stop

I knew we were limited in time so this was the best place to stop. All of this took about an hour.
On the plus side, none of the kids wanted to stop and are really looking forward to the next session. My daughter and son continued their "discussion" about whether or not it was a good idea to give a grubby goblin their money...
Another point. My son loves minis and was really pumped to play with minis for this session. We
partially used minis. They each picked one mini to represent their character and we used the minis to show their marching order. My son moved his mini around when his character was talking, but we didn't use them during combat. I used graph paper and drew the scene as it unfolded. None of the kids thought twice about the minis during it. They all just used their imagination. I thought it was impressive when we didn't use minis in my normal D&D group of adults. Now I'm doubly impressed. I thought for sure the kids would want to use the minis for combat. This was literally the draw for my son. Before we started he wanted to know when we'd play the 'mini game'...
I can't wait to play again. Pretty awesome to have my own home grown gaming group!