Can characters be summoned into a unit?
The rules for Summoning Spells (Nagash Book 1, pg 14) state that "the Summoned unit must be deployed wholly within the spell's range and at least 1" away from all other units, buildings and impassable terrain."

The Spell "Kandorak - The Harbinger" (Nagash Book 1, pg 15) does not state that the charcter summoned has an exception to this rule.