Entering into HTH with Megahex creatures

[stashhound]

Thank you all for taking the time to think about and reply to my question. I think I will rule that small creatures can willingly enter into hth from the front or side hexes at the end of movement. Allowing for the larger creature not to be engaged. So he can still engaged other same sized opponents while being attacked by the smaller opponent. If the smaller creature attempts this then the larger creature gets a roll vs dex. A save roll if you will. If he makes this roll he gets an attack of opportunity on the smaller creature. Once engaged all attacks on the smaller creature are considered rear attacks. But he can only be hit by small weapons without danger of damaging the large creature he is attached to.