Flying charges and landing

Imagine two enemy units, one behind the other with maybe an inch between them. I have a wyvern (flyer, large target) which can both see and reach either unit. Now, let's say I want to charge the second enemy unit, the one behind the first. Can I still do it if I have nowhere to land? Do we move the unit back to make space, or is the charge impossible?

On page 21 of the Rulebook it states that in the event that it is impossible to properly align units because of interposing terrain, other models, or whatever, it is acceptable to move the charged unit to allow the charger to get in. So, I would say yes, you can charge. The old "bunker" formation will not work against monstrous flyers that can see over and fly over intervening models/units.

Its a tricky interpretation, because I think it hinges on whether you are moving the enemy unit to align your monster or to make its charge move. We know that interposing models and terrain can block a charge move and make the charge fail.

The reason I ask is that a flying monster is a great answer to vampire lords, but what would happen if they are bunkering behind blocks of undead? I don't want this rules question to arise in a tournament.

I read in the rulebook also where it states that "the most important rule" should be used and that the charged should move models out of the way. I will have to review it in more detail, but it basically renders the "bunker" formation moot against monstrous flyers.

Flyers cannot land on formations unless charging them. The question is, does charging the second unit constitute "landing" on the first unit which was not charged?

I wonder that GW never addressed this in a FAQ

Ovich wrote:Flyers cannot land on formations unless charging them. The question is, does charging the second unit constitute "landing" on the first unit which was not charged?

I'm obviously of a particular mind, but I believe the rulebook answers this when it states that you should realign the charged unit to let the charger get in, if other models are in the way. Therefore, if the flyer has no room to land, realign the charged unit to let it land.