When you order the a.i. to attack something, they'll try and do so to the best of their ability, but if they're being attacked by something, they'll receive a 'dynamic goal' to take evasive action and to start defending themselves. If you disable them receiving dynamic goals, they won't just try and attack to the best of their ability, it will be literally the only thing on their mind.
In your case, if the dragons are straying too far from the convoy because they're engaged with an allied wingman, when you change their order from attack-any to attack, its possible they'll try to disengage from the fight, and focus on the convoy ship. But if the wingman then gets on their six and starts shooting them, they'll probably try and defend themselves again. If they have the no dynamic goals flag in this case, they'll just make a beeline for the new target and ignore the wingman on their behind.
Of course, that risks them becoming easy picking as they disengage from the wingman they were fighting before.
Hmm, that's worth considering.
I don't want to not have dragons in the mission, but it's starting to seem like, them being naturally evasive and all, it is inevitable that they will wander.