How can I change the creature ID by adding it as an NCF file?

@Mokara - a full set is called a set of creatures consisting of a basic creature and its two upgrades! The trick is this... when the map generator generates random monsters, usually a slot in the squad can be occupied by the basic creature and sometimes one of the two upgrades... i.e., to put it simply... 300 = basic, upgrade = 301, and alt-upgrade = 302! But if you have 300 = basic, and 307, for example, is an upgrade, and 309 is an alt-upgrade, then it will be illogical!