why not make it work like that:
Alien will remember any soldier he spots in his field off view for N turns where N = intelligence, other aliens are not aware of these soldiers
Alien will make other aliens remember any soldier he spots in his field of view for K turns where K = group intelligence (new alien stat)
Alien will pass his memory of soldiers to any other alien that is with his field of view for M turns, where M = telepathy (new alien stat, optional, very complex to implement but could be helpfull to create chain of memory strategy for aliens, so xcom can pass grenades and aliens could pass positions of xcom soldiers that way)
So IQ = 5 and Group IQ = 1, means that alien will remember spotted soldier for 5 turns + he will make other aliens remember them for additional 1 turn
Using this engine we could implement standard behavior from X-COM but also bring much more for mods.
Tom