Umm I think there may be a missunderstanding here. The rules you are referring to start by saying that you may not enter an enemy ZoC unless you are engaging that unit / formation (1.7.3). During an engage move, each unit can move where it likes, but once it enters the ZoC of an enemy unit, it must then move directly towards that enemy unit. Once the enemy unit is contacted (base-to-base), it loses its ZoC for the rest of the engagemen; so other assaulting units may then penetrate the enemy formation to attack units in the middle of it.
However, Thurse's original question effectively asked whether the ThunderHawk could assault the Leman Russes
through the Sentinel's Zoc, and the brief answer is
No; you can only enter the ZoC of the formation that you are assaulting.
There has been an amendment to this in the FAQ which at first glance seems to remove this particular restriction. Yme-loc and I asked about this over on the
SG forum. Neal Hunt's answer there was to the effect that you cannot land in the ZoC of the sentinels without assaulting them. The ammendment removes this restriction in an arcane situation where the scouts ZoC projects from behind the target of the charge, and would have to be traversed in the last few millimeters before contacting the target. In your case, if the Sentinels surround the 'Russes such that their Zoc covers them, then one or more of the sentinels must be destroyed to remove their ZoC before the ThunderHawk can land (and note Broken units still exert a ZoC).
However, as the 'Russes are a large formation, it would seem to be possible for the THawk to land on the tanks but outside the ZoC of the sentinels, barging some tanks out of the way as it did so. The troops inside could then engage the 'Russes as they enter the tank's ZoC before crossing the scout's Zoc to do so (
assuming there is enough space for them to deploy of course!!).
Teleporting troops have exactly the same problems - they must land outside the ZoC of the enemy, and so cannot land between the Sentinels and the 'Russes if there is no area free of enemy ZoC.
