samm why dont you just ask them to do as you ask as you made the mission for this purpose?
if they start saying they dont give a watermelon then im sure the guys in the mission who ARE trying to follow the plan will soon tell them they dont like it either.
I make many missions and im often bawling out people for ignoring flight plans but most of the time these guys are new and dont know how to follow a route or fly in formation.I tend to ignore them if they dont respond unless they are giving away a position or something.
Also if they take up precious slots you'll have to start adding a few more spots so you can account for wastage to these people.
I try to get a few people i can rely on in each flight (like squadmates or drunky, saw,or squads like dmd's or FB's) so i know at least 1 or 2 will do whats asked.You will have to learn to do the same

Also you need to make sure they all know the plan as they are waiting for the start.If its NOE keep saying it in text. Make sure flight description has the TARGET in it, Use different planes for different targets so you can direct them easier, ie
'all 190s hit VH, all me110s hit Town, all p47s hit Fighter hangers'
this makes it clearer to the newbies and helps keep the flocks together.
oh and remember BAWL EM OUT if they dont follow the mission plan!!!

you took the time to make the mission samm, you have every right in my eyes to have a go at those who are spoiling it.