I would strongly suggest you do not do that, unless you want to end up in court like the two women from the teacups did a couple of years ago.
Not that I think Aubriee would do anything but someone else might.
This reminds me of something that happened a couple of trips ago. TSM was about a month or so old, we had never ridden it and we had gotten in late at DHS so all FP's were gone. The line was about 70 min long, we decided to brave it and go right in. We made friends with the families in front and behind us, we were talking, they were first timers and we were sharing tips etc and their kids were telling us all about what they had done so far, it was keeping us all entertained. So after 40 minutes of peaceful line waiting we see this lady with two girls in tow literally pushing and shoving her way up front, when someone asked to please don't push she would say: "Oh, we are meeting up with people up front" and kept going. She got a group or so behind us all and a group of adults that were from the DIS (They had DIS stuff on their lanyards that's how I figured it), asked her what she needed.
She went on this pity party thing about how the cousin of her little girl was up to the front and she sooooo wanted to ride with her cousin so they HAD to get to the front that instant. One of the DISers pretty nicely told her: "Ma'am I didn't see you leave the queue for the last 40 minutes, so I am sorry but that's line cutting". Everybody around them sorta looked up, and the families around us actually commented that they were glad they said something.
Well the lady flew off the handle from then on. There was a lot of "how could you's" "Adults ought to be ashamed!" "Disney is ALL about the kids so adults should move over" blah blah blah. She berated the group for another good 10 minutes as we slooowly moved forward. Everybody looked at her like she had just grown a second head, she was loud, obnoxious and wouldn't let up. The Disers didn't engage her at all anymore.
Finally we made it to one of the spring loaded sections of the queue, she smugly pushed it and moved onto another section that was further up queue, then loudly commented something about "That ought to teach them a lesson, telling me what I can or I can't do!". So she kept on pushing and shoving talking about this cousin. Just 5 minutes after she stopped in the line, close to where you pick up the 3D glasses and just stayed on that one spot in line

. We all just stared confused, and someone up ahead commented: "I guess the cousin was imaginary" the families around us said: "I guess her kids are special and deserve a spot up front but not ours, let alone adults!"
Their kids asked if that was allowed. The parents explained no it wasn't, and the kids were confused as to why nobody was doing anything. Then the parents had to explain the whole: "Well, we obey the rules, some people bend them, and this is how we make it in our home", etc etc.
We have also had people walkie-talking to their party outside when they were nearly through the line: "Hello, I am nearly to the front, you guys might want to start making your way up here!"

If someone looks at them funny they just say: "What? Everybody does it and no one says anything, so more power to me!" That there is not only class, but good planning AND coordinating!
It really gets annoying when a few use their kids as an excuse to act like toddlers and have a tantrum to get whatever they want, if enough of them do it when someone actually has an emergency or does things the right way people loose all sympathy. DH and I go to WDW alone, not by choice mind you, we have never been so incredibly lucky to be able to have kids, it is something that really saddens me, so when a few people act like we ought to be second class citizens in Main street USA because we don't have kids with us it really makes me sad.
My point is:
1) Getting to the parks early guarantees short waits, if you travel with younger kids this is the best time to go and doesn't lend itself to potty break madness. (We travel with friends that bring their 3 year old DS with autistic and ADHD symptoms and really is the best time!)
2) The fastpass machines are really not that far from the entrance of the attractions, waiting to the side while your runner gets some won't delay you that much, unless you sent your runner all the way across the park, in which case I would recommend you ride first, then join them outside, if it is still early, odds are you can ride yet again with them when you get out.
3) I don't have a problem if there is an emergency and need to get out, do seek assistance from a CM as you leave so they can lend you a hand getting back.
4) To those that abuse people's good intentions and sympathy, please STOP IT! You are making it harder and harder for some of us to really care when it counts.