I’m playing Murne Rin in a Jabba’s Realm campaign. I am within 3 spaces of an Elite Jet Trooper, the Threat Level is 5, I have an action available and I have no strain, so I may perform False Orders. So far so good. But, now, since the Elite Stormtrooper that is within two spaces of the Elite Jet Trooper is the target of the attack, may I invoke the Jet Trooper’s Fly-By ability for the attack (adding a blue attack die to the attack roll and giving him two additional movement points which he may or may not be able to use depending on whether he has already be activated or not)?

I believed that I could and we did play it this way, however I want to make certain what the proper play is for future games.

Yes, Murne controls the figure during the attack and has access to all of the abilities of that figure. (Even its attachments if any, and passive bonuses from other imperial class cards that do not have "may" or costs that only the imperial player can pay, because the cards are still under imperial control.)

Also, for spending the mp:

Thanks for the answer. While we were playing False Orders correctly, it appears we’ve been doing movement points gained outside of an activation wrong. We were marking them with tokens then adding them to a move action if the character activated later that round. And any accumulated move points that were unused were lost at the end of the round. I take it this means Solidarity allows me to move two points right after a character within three spaces triggers it and completes their move?

While we’re on the subject of Solidarity, that ability only triggers if the character that moves starts within three spaces, not if during their move they close to or pass within three, right?

Yes, the movement points from Solidarity have to be used immediately when the other hero performs a move , even before the other hero gets to spend the gained movement points.

Note that the Move action allows to perform a move , which gives movement points according to speed. It does not move the figure. Spending movement points moves the figure. Solidarity trigger off performing a move , not moving a figure.

Another hero could trigger Solidarity twice if ends movement and performs both moves within 3 spaces of Murne. Possibly suffering 1 strain for 1 mp to first spend it to move closer to Murne before a first Move action. Then the hero can spend 2 mp to 'run after Murne', and Move again to perform another move. So, Murne is pretty mobile with Solidarity .

Also note that if Gideon is in play, his Command allows to perform a move (not an action), which also triggers Murne's Solidarity , if she is close enough to the hero performing the move.

Thanks again, for the answers. This shall definitely improve my character’s effectiveness.