Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

I multi-assault into two one-model units:

C-x-x-x-x-x-x-x-x
B-----------x x x-A-x x

For the purpose of this diagram the multi-assault charge was done 100% properly
Unit A is a character. Unit B is not.
My character (C) is outside 3" of Unit A, not engaged with Unit A, just Unit B.
I don't declare any challenges, my opponent immediately declares a challenge on me.
I claim that my character is out of engagement with Unit A and so can't be challenged.
Opponent says since my Character is engaged at all with Unit B means he can challenge me even if I'm 6" away period cause it's all one combat.

Please explain the right answer to this.

Your opponent is correct.

All the challenge rules call for to accept or make a challenge is that the character is engaged in combat.

As above. A multicombat is considered to be a single combat, and all the challenge rules require is to be engaged in combat