Hi Xillix,
I've managed to do this mission.
-First I noticed that "Rocket 01" the B-1B start taxiing around 16:43 instead of 16:40.
-Second, at this time clock "Chevy 04", the second M2000 flight, also start to taxi. They're supposed to wait behind you, but I don't move and let them go and take-off. (I answered the radio normally the all-time, even if I don't move)
-During that, Rocket 01 slowly rolls on his taxiway. Once he gets close to the end of it, I start taxiing and hold short on alpha 03L, as GRND asking. (Don't cross to hold short 03R like i did first, mission will fail)
-Tell GRND you're holding short 03L while the B-1B enter 03R to take-off.
-GRND will reply you to stay on position because the runway is in use.
-When the B-1B is airborne, GRND will allow you to cross 03L and contact TWR when holding short 03R
-Take-off and the mission begin ! (cool one btw)
Maybe it works too if you taxi first, as expected, with "Chevy 04" behind, hold short 03L without reporting to GRND, but wait for the B-1B to enter the runways and then hit the dialogue...
I hope it will help, here's also a video I saw to help me visualize the ground taxiing sequence (unbugged)
