Sure, if you're being honest about the danger he faces in his role.  From Rosie's post I thought you guys were going for something a little less up-front about it, but this is definitely a valid option as well.

6:38, Today: Geezer Ridire rolled -2 using 4 Fudge dice ((-1, -1, 1, -1)).

Larsen still seems a little reluctant, but he agrees to go in disguise and be the point person for your plan.

As you head back to town to get the paint, you think you see the soldiers giving each other some surreptitious looks.  No one says anything to the two of you though.

Unspecified Negative Aspect has been added to the situation.  You'll find out what it is if/when it kicks in.

Disguise is in place - what's the next part of the plan?

What do you think, Rosie?  I believe this was your idea.

I suggest we try to find a small group of the Children, hopefully only two or three and test out his disguise. If all goes well, approach a larger group and try to rouse them to action. Perhaps we can kind a group that is already a bit rowdy?

Any addendums or alternatives happily accepted.

I guess we’ll send our imposter out in search of a small group of Children, while we watch from afar.

"Watch from afar" as in physically close enough to see him, and intervene if necessary?  That will require one of you to make a Diligence roll, which will eventually be opposed by the Children.

Or if you have a different idea in mind then let me know.

No, that sounds good.  Shall I roll now?

Yeah, go for it, and then we'll get into how the scene plays out

15:31, Today: Geezer Ridire rolled -1 using 4 Fudge dice with rolls of 0, 1, -1, -1.  dilligence. – -1

You return to the forest, same area where you were before, and wait to activate your trap.  After a little while a guard patrol does approach, six strong, holding spears.  Your man in disguise waves his arms to get their attention, and they hurry over to him and start talking.  There is a problem though - you don't know their language, and neither do any of the soldiers, including Larsen.  He glances around nervously.  Another one of the guards, with the darkest skin, steps up and shouts in Larsen's face.  The other guards all turn a shade or two lighter, but of course Larsen cannot.  Before he can do anything, or any of you for that matter, two of the sea children grab him.  The guard leader quickly scans the area where you thought you were hidden and locks eyes with Geezer.  It continues shouting, not that you can make any sense of it.  But you also notice a faint electric hum coming from it, or something that it is carrying.

GM, for the NPC Children, rolled 3 using 4 Fudge dice.  spot hidden enemies +1.
-they succeeded with style against Geezer's diligence, and get a boost called We Have a Hostage

Geezer shouts, waves his hands and tries to start a parlay.  But at the same time, he tries not to expose himself too badly.

Their leader points at Geezer, then points down at the ground in front if it, and glares at you impatiently.

Rosie tries her best to stay hidden, waiting to see what happens next. She furtively searches the area for more of the Children.

Supposing that means he’s been personally invited to parlay, Geezer reluctantly steps out.

The lead guard (Child?) turns an even darker shade of blue as it continues to shout in their language.  When Geezer approaches, two of the others move up to flank him.  You notice right away that one of them is holding some sort of thick elastic band.  It is stretching it between both hands right now, wide enough to, say, bind a human's two wrists together.

Rosie does not see any more of the Children around, only this one group.

“Do any of you speak our language?  We can’t understand the jibber-jabber that you speak.”

The only response you get is more jibber-jabber, and the others moving in close to try to bind your wrists in the elastic band.  Do you let them?

No.  I take a step back with my hands held up, indicating I’m not surrendering but want to parlay.

It shouts more, and the ones that are still holding weapons point them at you rather emphatically.

I rush back and order everyone to prepare to fight.  These Children are most unreasonable!  But I hope to make them Children of the Grave.

Geezer, they've got you nearly surrounded already, so if you're trying to break free and get back to where you once were armed then you'll need to roll something or other against difficulty 4

Any suggestions regarding what I should roll against?  These Children sure are a bunch of sneaky rat-finks.
This message was last edited by the player at 15:36, Mon 04 Mar.

These are the options I'm seeing:
Guile - if you try to be extra sneaky right back at them
Prudence - if you take the extra couple of seconds to watch for a good opening before you move
Vigor - if you are relying on brute force and speed to get past them

If you go with Guile or Vigor, you can be pretty confident that a failed roll will result in you getting injured.  A Prudent action will carry less risk of injury, but a failed roll gives them a better chance to successfully bind you.

Rosie, what are you doing while all this is going on?
This message was lightly edited by the GM at 01:35, Sat 09 Mar.

I will step forward in preparation of helping Geezer if it looks as if he can’t break away.