starting units

i was wondering if there is a way to change or add to the starting units in a custom game and still having the random start location
ie human starts with 5 pesents and ONE captain
undead added a frost worm and so on like that

There is a function that returns a player's start location

well thats good to know but how and where would i find all this

In the trigger editor. Just create the bonus unit with a trigger at player's start location when the map starts.